MODERN   STEEL 
ANALYSIS 


MODERN    STEEL 
ANALYSIS 

A    SELECTION    OF    PRACTICAL 

METHODS  FOR  THE  CHEMICAL 

ANALYSIS  OF  STEEL 


BY 

J.    A.    P  I  C  K  A  R  D 

B.Sc.  (Hons.  Lond.),  A.R.C.Sc.,  A.I.C. 

Carnegie  Research  Scholar  of  the  Iron  and  Steel 

Institute,  Fellow  of  the  Chemical 

Society  of  London 


PHILADELPHIA 

P.   BLAKISTON'S   SON  &  CO. 

1012  WALNUT  STREET 
1914 


Printed  in  Great  Britain 


PREFACE 

IN  writing  the  present  book  it  has  been  the  endeavour 
of  the  author  to  condense  into  a  small  space  practical 
methods  for  the  exact  estimation  of  all  those  con- 
stituents of  steel  which  are  of  fairly  common  occurrence. 
It  is  hoped  that  the  book  will  be  found  useful  by  steel 
analysts  who  do  not  possess  either  the  time  or  the 
facilities  for  personally  sifting  the  mass  of  literature 
which  is  annually  published  on  the  subject,  and  that 
it  will  also  meet  the  requirements  of  third  and  fourth 
year  students  who,  after  a  general  training  in  chemistry, 
are  desirous  of  obtaining  some  practical  experience  in 
analysis  which  is  commercially  important.  No  attempt 
has  been  made  to  give  a  comprehensive  description  of 
all  the  processes  used  in  the  analysis  of  steel,  but  the 
methods  detailed  have  been  selected  for  their  practical 
utility.  A  section  on  general  procedure  has  been 
included  primarily  to  meet  the  needs  of  students'with- 
out  experience  in  chemical  practice,  but  it  is  hoped  that 
some  of  the  hints  contained  therein  may  also  be  of 
service  to  other  chemists. 

Methods  for  the  estimation  of  tantalum,  columbium, 
tin,  boron,  and  a  few  other  unusual  constituents  of 


Vi  PREFACE 

steel  have  not  been  included  in  the  present  volume,  but 
should  this  little  work  prove  useful  to  chemists  it  is 
hoped  to  include  them  in  a  subsequent  edition. 

The  author  desires  to  express  his  indebtedness  to 
Messrs.  C.  H.  and  N.  D.  Ridsdale,  of  Middlesbrough,  for 
permission  to  publish  details  of  their  well-known 
mechanicalized  methods. 

J.  A.  P. 


CONTENTS 

PAGB 

GENERAL  PROCEDURE  1 

ALUMINIUM  15 

ARSENIC  17 

CARBON  19 

CHROMIUM  29 

COBALT  33 

COPPER  36 

HYDROGEN  39 

MANGANESE  42 

MOLYBDENUM  52 

NICKEL  54 

NITROGEN  58 

OXYGEN  62 

PHOSPHORUS  68 

SILICON  74 

SULPHUR  79 

TITANIUM  88 

TUNGSTEN  92 
vii 


Vlll  CONTENTS 

PAOX 

URANIUM  94 

VANADIUM  96 

NOTE  ON  THE  ESTIMATION  OF  PHOS- 
PHORUS IN  STEELS  CONTAINING 
ARSENIC  103 

ATOMIC  WEIGHTS  105 


APPENDIX  I-SOLUTIONS  109 

APPENDIX      II— ANALYSES      OF      DIF- 
FERENT STEELS  AND  ALLOYS  118 

INDEX  125 


GENERAL  PROCEDURE 

THE  following  remarks  are  intended  primarily  to  guide 
students  who  have  pursued  a  general  course  of  training 
but  are  without  practical  experience  of  procedure  in  a 
routine  laboratory.  Chemists  daily  engaged  in  analysis 
may  consider  many  of  the  statements  obvious  or  un- 
necessary, but  it  is  the  author's  experience  that  students 
who  have  attained  a  sound  theoretical  knowledge  are 
frequently  lacking  in  the  ability  to  perform  operations 
in  the  simplest  way  necessary  to  ensure  accuracy. 
Analytical  chemistry  as  taught  in  many  colleges  is, 
to  a  large  extent,  far  too  academic  in  its  quality  :  pre- 
cautions are  insisted  upon,  but  no  account  is  taken  of 
their  relative  value.  For  example,  before  weighing  an 
ignited  precipitate  of  barium  sulphate  the  addition  of 
a  drop  of  nitric  acid  followed  by  a  drop  of  sulphuric 
acid — to  convert  any  sulphide  formed  by  reduction  by 
the  filter  ash  back  into  sulphate — and  re-ignition  is 
always  insisted  on,  but  the  complete  insolubility  of 
barium  sulphate,  however  precipitated  and  however 
washed,  is  a  matter  of  faith.  With  proper  ignition  the 
error  introduced  by  neglect  of  the  former  precaution 
can  hardly  exceed  5  per  cent,  of  the  weight  of  the 
precipitate  in  the  most  extreme  cases,  whereas  if  the 
precipitate  be  not  obtained  by  adding  the  barium 
chloride  solution  slowly  to  the  boiling  sulphate  solution 


*&-,:;/        MODERN   STFEL   ANALYSIS 

only  60  to  70  per  cent,  of  the  barium  sulphate  may  be 
precipitated  from  dilute  solutions  in  twelve  hours,  and 
if  the  precipitate  is  washed  with  dilute  hydrochloric  acid 
the  greater  part  will  be  dissolved  from  off  the  filter 
again.  Again,  rapidity  is  hardly  considered,  nor  is 
there  any  attempt  to  avoid  the  performance  of  un- 
necessarily laborious  operations.  For  instance,  a  sample 
is  weighed  out  by  difference  weighings  from  a  weighing 
bottle,  which  establishes  the  weight  taken  accurately 
to  about  1  in  50,000,  while  duplicate  determinations  will 
not  agree  to  the  third  significant  figure. 

Weighing.  Analysts  are  chiefly  concerned  with  the 
weighing  of  the  amount  of  sample  taken,  the  final 
ignited  precipitate,  and  absorption  tubes. 

Weighing  out  Sample.  It  is  usually  found  desirable 
in  practice  to  adjust  the  weight  of  the  sample  to  an 
even  number  of  grams,  or  to  a  convenient  factor  weight ; 
as  this  simplifies  calculations,  reduces  the  number  of 
notes  to  be  made,  and  minimizes  the  liability  to  errors 
in  weighing.  This  is  most  readily  managed  by  using 
a  small  scoop,  hammered  or  stamped  out  of  aluminium 
or  other  sheet  metal,  exactly  counterpoised  by  a  suitably 
adjusted  lump  of  metal  placed  in  the  pan  carrying  the 
weights.  After  weighing,  the  sample  is  tipped  out  of 
the  scoop  into  the  beaker  or  flask,  and  if  necessary  the 
scoop  is  brushed  out  with  a  fine  camel-hair  brush,  but 
usually  a  smart  tap  will  remove  everything.  In  most 
analyses  it  is  unnecessary  to  weigh  the  amount  taken 
more  accurately  than  to  a  milligram,  although  the  moral 
effect  of  the  fourth  place  is  sometimes  stimulating. 

Precipitates.  A  good  many  precipitates,  such  as 
silica,  barium  sulphate,  aluminium  oxide,  are  most  con- 


GENERAL   PROCEDURE  3 

veniently  weighed  by  brushing  out  of  the  crucible  into 
the  balance  scoop,  taking  precautions  against  loss  by 
performing  the  operation  over  a  sheet  of  smooth  paper. 
In  the  case  of  powdery,  non-hygroscopic  precipitates 
this  procedure  is  to  be  recommended  not  only  on  the 
grounds  of  speed  and  convenience,  but  also  for  its 
accuracy,  as  the  chemist  is  thereby  freed  from  any 
doubt  as  to  the  fluctuation  in  weight  of  the  crucible 
and  is  certain  that  the  weight  obtained  is  that  of  the 
precipitate.  Not  all  precipitates,  however,  can  be 
brushed  out  in  this  manner,  and  in  these  cases  the  usual 
weighing  in  tared  crucibles  is  necessary.  Very  hygro- 
scopic precipitates,  which  are  rare,  may  be  weighed,  if 
the  greatest  accuracy  is  desired,  in  crucibles  enclosed  in 
stoppered  weighing  bottles  ;  but  usually  it  is  sufficient 
first  to  adjust  the  weights  roughly,  and  then  to  place 
the  crucible  in  the  pan  and  complete  the  weighing  as 
quickly  as  possible. 

Absorption  Tubes.  The  weighing  of  absorption  tubes 
calls  for  no  special  mention.  They  should  expose  as 
small  a  surface  as  possible  and  should  be  polished  with 
a  soft  leather  before  weighing.  After  polishing,  for  the 
greatest  accuracy  they  should  be  left  in  the  balance 
case  for  ten  minutes  and  then  weighed ;  neglect  of  this 
precaution  may  lead  to  an  error  of  as  much  as  two 
milligrams.  Geissler  potash  bulbs  and  other  fragile  and 
intricate  apparatus  are  quite  unsuitable  for  practical  use. 

Precipitation.  To  obtain  precipitates  in  such  a  con- 
dition that  they  filter  readily,  that  is  to  say  in  moderately 
large  and  compact  particles,  is  one  of  the  operations  in 
which  the  value  of  practical  extended  experience  is 
inestimable.  The  conditions  governing  the  formation 


4  MODERN   STEEL  ANALYSIS 

of  proper  precipitates  follow  no  general  rule,  but  vary 
from  case  to  case.  Lead  molybdate  and  cobalt  am- 
monium phosphate  are  practically  unalterable  unless 
the  liquid  in  which  they  are  precipitated  is  well  boiled. 
In  the  basic  acetate  precipitation  of  iron  the  liquid 
must  be  raised  to  boiling-point,  but  if  boiled  the  pre- 
cipitate becomes  slimy.  Cuprous  thiocyanate  is  most 
satisfactory  if  precipitated  from  cold  solutions  after 
vigorous  stirring,  while  magnesium  ammonium  phos- 
phate must  be  precipitated  from  thoroughly  cold 
solutions  which  are  well  stirred  or  shaken.  In  some 
cases  large  excesses  of  precipitant  are  desirable,  in  others 
the  smallest  possible  excess.  No  general  rule  can  be 
formulated  and  knowledge  of  conditions  necessary  is 
only  to  be  gained  by  experience ;  for  although  it  may  be 
possible  in  each  case  to  define  exactly  the  precautions 
to  be  taken  it  is  undesirable  to  burden  a  description  with 
small  details  which  are  commonplaces  to  the  man  of 
experience. 

Filtration.  This  operation,  which  by  faulty  mani- 
pulation may  easily  occupy  more  time  than  all  the 
other  operations  of  analysis  together,  when  performed 
with  skill  is  one  of  the  most  rapid.  A  volume  of  300  c.c. 
should  pass  through  in  five  minutes  or  less,  and  the  rate 
of  flow  should  be  but  little  retarded  when  the  precipitate 
has  been  transferred  to  the  filter.  Generally  speaking, 
warm  solutions  filter  better  than  cold,  and  acid  solutions 
better  than  alkaline,  but  the  most  important  point  is 
the  proper  arrangement  of  the  filtering  medium.  When 
using  filter  papers,  funnels  with  deep  ribs  or  flutings  on 
their  inside  conical  surface  are  much  to  be  preferred  to 
plain  funnels.  Plain  funnels,  even  with  a  well-fitting 


GENERAL   PROCEDURE  5 

filter  paper,  in  addition  to  filtering  rather  slowly  some- 
times allow  fine-grained  precipitates  which  go  through 
the  paper  to  be  retained  between  the  glass  and  the 
surface  of  the  paper,  with  the  result  that  when  the  filter 
paper  is  removed  for  ignition  some  of  the  precipitate 
sticks  to  the  glass  and  is  then  rather  difficult  to  transfer 
to  the  crucible  ;  or  it  may  even  be  overlooked  and  lost. 
Pulp  Filtration.  Filters  of  almost  any  degree  of 
openness  or  fineness  may  be  obtained  by  the  use  of 
filter-paper  pulp,  and  for  a  given  efficiency 
of  separation  filtration  through  pulp  is 
quicker  than  through  folded  papers.  A 
pulp  filter  is  prepared  in  the  following 
manner :  A  number  of  filter  papers  are 
torn  (not  cut)  into  small  pieces  about  half 
an  inch  square  or  less  and  placed  in  a  large 
flask  about  half  filled  with  water,  preferably  FlG-  *• 
hot.  The  flask  is  then  stoppered  and  the 
contents  thoroughly  shaken  until  the  filter  paper  is 
completely  broken  up  into  shreds.  On  the  score  of 
cheapness  filter-paper  clippings  are  to  be  recommended 
and  serve  equally  well.  The  filter  pad  is  now  prepared 
by  placing  a  perforated  porcelain  filter  disc  in  the  neck 
of  a  plain  funnel  (see  Fig.  1),  whose  stem  has  been  cut 
off  square  but  not  unduly  shortened.  Water  is  poured 
in  to  cover  the  disc,  and  pulp  suspension  added  in 
sufficient  amount,  keeping  the  stem  closed  meanwhile 
with  the  finger.  The  filter  plate  is  adjusted  in  the  neck 
of  the  funnel  with  a  glass  rod  and  the  finger  removed, 
when  the  pulp  sinks  down  and  forms  a  pad.  This  is 
now  consolidated  by  judicious  pressure  with  a  flat- 
ended  glass  rod,  more  or  less  pressure  being  used  according 


6  MODERN   STEEL   ANALYSIS 

to  the  fineness  of  the  precipitate  to  be  separated.  The 
edges  of  the  pad  are  conveniently  tucked  in  by  swirling 
a  fairly  rapid  stream  of  water  from  a  wash  bottle  cir- 
cumferentially  over  it.  With  such  a  pad  even  a  sulphur 
suspension  may  be  filtered  out ;  while  the  rapidity  of 
filtration  is  very  satisfactory,  and  the  washing  of  the 
precipitate  greatly  simplified  because  all  the  washing 
liquid  passes  through  the  precipitate  and  there  are  no 
filter-paper  edges  to  be  carefully  washed.  A  filter 
pump  may  be  used  in  conjunction  with  these  pads 
without  fear  of  sucking  through,  but  attempted  accelera- 
tion with  a  pump  in  most  cases  produces  only  a 
temporary  acceleration,  as  with  other  filters,  the  last 
state  being  worse  than  the  first. 

Filtration  through  Asbestos.  Many  liquids  which  can- 
not be  filtered  through  filter  paper,  such  as  permanganate 
and  caustic  solutions,  may  be  filtered  through  ignited 
asbestos.  Ordinary  asbestos  is  ignited  in  a  muffle  and 
made  up  into  a  suspension  with  water  in  the  same  way 
as  pulp,  and  a  filter  prepared  in  the  way  just  mentioned. 
Special  filtering  asbestos  can  be  obtained,  but  is  much 
more  expensive  than  the  ordinary  variety  and  little 
better.  It  is  not  advisable  to  use  asbestos  in  filtration 
of  acid  liquids  where  contamination  with  metallic  salts, 
particularly  those  of  iron,  aluminium,  and  magnesium,  is 
prejudicial,  as  although  an  improvement  may  be  made 
by  extracting  with  strong  hot  hydrochloric  acid  it  is  prac- 
tically impossible  to  extract  everything  soluble  in  acids. 
Cotton-wool  Filtration.  Cotton-wool  may  be  made 
use  of  very  advantageously  for  certain  filtrations,  as  it 
is  practically  ashless  and  withstands  the  action  of  con- 
centrated hydrochloric  acid,  1*2  nitric  acid,  and  fairly 


GENERAL   PROCEDURE  7 

strong  sulphuric  acid  very  well.  A  cotton-wool  filter 
is  very  conveniently  made  by  pushing  a  pad  of  cotton- 
wool about  |  in.  long  into  a  long  tube  of  J  in.  bore 
supported  in  a  burette  stand.  This  method  of  filtration 
is  particularly  useful  in  the  estimation  of  graphite  in 
pig-iron,  as  after  filtration  and  washing  are  complete 
the  pad  is  pushed  backwards  out  of  the  tube,  thereby 
efficiently  cleaning  the  walls,  and  may  be  burnt  off  at 
the  mouth  of  the  muffle ;  the  residual  graphite  being 
then  weighed. 

Evaporation  and  Baking.  These  operations  are 
performed  on  a  hot  plate,  which  may  be  conveniently 
constructed  of  a  sheet  of  steel  J  in.  thick,  measuring 
about  2  ft.  by  18  in.  The  plate  may  be  supported  on 
iron  legs  or  on  bricks,  and  should  have  burners  disposed 
beneath  it  so  that  a  range  of  temperature  is  obtained 
from  the  highest  temperatures  directly  over  the  burner, 
which  should  impinge  on  the  lower  surface,  to  the  com- 
paratively cool  corners  most  distant  from  the  flame.  A 
large  spreading  flame  particularly  suitable  for  heating 
hot  plates  may  be  obtained  by  using  an  ordinary  bunsen 
burner  whose  jet  has  been  replaced  by  a  hole  J  in.  in 
diameter.  Evaporations  can  be  speedily  carried  out  on 
a  hot  plate  as  the  beaker  can  be  placed  on  a  part  only 
just  cool  enough  to  avoid  spitting.  When  evaporated 
to  complete  dryness,  Jena  beakers  may  be  placed  on  the 
hottest  part  of  the  plate  and  thoroughly  baked  without 
the  least  danger  of  cracking  the  glass  if  not  too  suddenly 
cooled  when  removed.  It  is  sometimes  convenient  to 
cover  part  of  the  plate  with  a  sheet  of  asbestos  on 
which  beakers  requiring  a  long  digestion  at  a  moderate 
temperature  may  be  placed. 


8  MODERN   STEEL   ANALYSIS 

Absolute  Value  of  Results.     Where  there  is  any 
doubt  whether  a  figure  obtained  as  a  result  of  an  analysis 
actually  represents  the  true  percentage  of  the  con- 
stituent in  the  sample,  the  most  satisfactory  confirma- 
tion of  its  accuracy  is  obtained  by  going  through  the 
same  series  of  operations  using  a  similar  solution  of 
known  composition.    This  is  nearly  always  possible, 
and  many  procedures  giving  rise  to  results  which  would 
be  erroneous  if  taken  at  their  face  value — especially  in 
volumetric  estimations — may  be  made  to  yield  satis- 
factory figures  by  taking  into  account  the  behaviour 
of  the  standard  or  the   blank  determination.     The 
standard  solution  should  always  be  of  as  nearly  as 
possible  identical  composition,  not  only  as  to  the  con- 
stituent under  consideration  and  iron,  but  also  as  to 
the  other  components  of  the  solution,  dilution,  acidity, 
&c.     Often  the  most  satisfactory  way  is  to  add  a  definite 
further  amount  of  the  doubtful  constituent  to  the 
sample,  carry  through  the  analysis  as  before,  and  see 
whether  the  increased  percentage  found  corresponds  to 
the  amount  added,  though  this  is  not  satisfactory  in  all 
cases.    By  this  means  a  greater  feeling  of  certainty  as 
to  the  meaning  of  the  result  is  obtained,  Lnd  the  personal 
equation,  a  very  important  factor  in  the  past,  can  be 
eliminated. 

Arrangement  of  Work.  This  is  perhaps  the  most 
important  thing  to  be  learnt  by  an  analyst  when  once 
he  has  mastered  the  elements  of  the  science.  The  dove- 
tailing of  operations  so  that  the  worker's  time  can  be 
fully  used  to  the  best  advantage  needs  experience  and 
forethought.  A  little  time  is  well  spent  at  the  beginning 
of  each  day  in  taking  stock  of  the  things  to  be  done  and 


GENERAL   PROCEDURE  9 

arranging  in  what  order  to  do  them.  There  is  then  no 
fear  either  of  time  being  wasted  or  of  overcrowding  any 
part  of  the  day  with  too  many  operations,  conditions 
which  almost  invariably  lead  to  imperfect  work  and 
want  of  accuracy.  It  is  perhaps  hardly  necessary  to 
indicate  that  long  evaporations  should  be  started  as 
soon  as  possible,  and  that  while  they  are  proceeding 
the  shorter  estimations  may  be  carried  out.  Filtration 
should  be  arranged  to  fall  in  batches,  so  that  the 
operator's  time  may  be  fully  occupied ;  for  it  takes 
but  little  longer  to  filter  six  solutions  than  one  if  done 
together,  though  separately  they  would  occupy  six 
times  as  long.  Economy  of  time  and  gas  is  ensured  by 
arranging  that  the  precipitates  to  be  ignited  are  all 
burnt  off  at  the  same  time  ;  and  it  takes  less  time  to 
make  twenty  weighings  one  after  the  other  than  it  does 
to  make  twenty  weighings  separately. 

Sampling.  In  taking  samples  from  specimens  of 
steel  the  object  usually  in  view  is  to  obtain  a  repre- 
sentative portion  of  the  material  in  a  shape  suitable  for 
analysis ;  but  sometimes  when  want  of  homogeneity,  or 
segregation,  is  suspected,  sampling  is  performed  with 
the  intention  of  revealing  this  variation  in  composition. 
Since  solidification  begins  from  the  outer  surface  of  a 
casting  and  the  impurities  in  the  steel  are  both  lighter 
and  more  fluid  than  the  pure  metal,  it  follows  that  the 
higher  parts  of  the  thickest  portions  of  the  casting  will 
tend  to  contain  a  higher  proportion  of  these  impurities, 
and  this  fact  should  be  borne  in  mind  when  looking  for 
local  variations. 

When  a  representative  sample  only  is  needed  material 
from  near  the  surface  should  be  avoided,  particularly 


10  MODERN    STEEL   ANALYSIS 

if  much  re-heating  has  been  performed  on  the  specimen, 
as  a  considerable  amount  of  carbon  may  have  been  lost 
under  these  conditions. 

The  method  of  taking  the  sample  calls  for  a  little 
notice.  The  usual  practice  is  to  drill  the  sample,  using 
as  large  a  drill  as  the  sample  will  take  and  the  power 
available  permits,  since  a  drill  is  the  most  economical 
tool  for  reducing  a  portion  of  the  specimen  to  a  handy 
size  for  manipulation  in  view  of  its  requiring  least 
power  for  removing  a  given  weight  of  metal.  Turning 
is  also  a  permissible  method,  but  filing  and  milling 
are  not  satisfactory — filing  because  the  file  teeth  are 
worn  away  and  contaminate  the  sample,  and  milling 
because  of  the  great  difficulty  in  cleaning  the  cutter  and 
the  trouble  and  expense  which  would  be  necessitated  by 
the  frequent  grinding  and  resetting.  Whichever  method 
is  employed  the  tool  used  should  be  sharp  and  used 
without  lubricant,  as  it  is  essential  to  avoid  studiously 
any  contamination  with  carbonaceous  material. 

The   following   list   contains   brief   instructions   for 
suitably  drilling  commonly  occurring  shapes. 

Bars.  Drill  transversely  from  side  to  side,  neglecting 
drillings  from  surface. 

Plates.    Drill  through  in  several  places. 

Ingots.  Drill  well  in.  Always  avoid  outside  layers 
and  top  of  ingot. 

Rails.  Drill  parallel  with  the  length  in  several  places. 
Carbon  may  vary  from  point  to  point,  and  the 
samples  should  be  kept  separate  and  examined 
for  carbon  segregation.  The  other  determinations 
should  be  carried  out  in  the  sample  from  the 
thickest  part. 


GENERAL   PROCEDURE  II 

Carriage  Springs.  Chop  off  and  drill  ends  trans- 
versely. 

Sample  Ingots.    Drill  from  face  to  face. 

Castings.  These  are  so  varied  in  shape  that  no 
general  instructions  can  be  given  except  to  avoid 
the  outside  and  top  parts. 

Useful  Apparatus.    There  are  a  good  many  simple 
pieces  of  apparatus  easily  made  by  any  good  carpenter 


FIG.  2. 

which  greatly  add  to  the  convenience  of  working  and 
minimize  loss  of  time.  A  good  draining  board,  a 
measure  rack,  a  beaker  rack,  and  a  filtering  stand  are 
really  invaluable,  and  the  forms  shown  in  the  illustra- 
tions have  been  found  quite  satisfactory. 

Draining  Board.  This  piece  of  apparatus  is  too  well 
known  to  need  much  description.  It  should  consist 
of  a  sloping  board  with  vertical  pegs  to  support  the 
apparatus  while  drying,  and  should  be  of  fair  size  and 
be  conveniently  disposed  to  drain  into  the  sink. 

Measure  Rack.    A  suitable  rack  may  be  made  by 


12 


MODERN   STEEL   ANALYSIS 


cutting  a  number  of  bays  with  straight  sides,  and  of 
widths  adapted  to  the  measures,  in  a  shelf.  The 
measures  are  suspended  in  the  bays  by  means  of  the 
flanges  at  the  bottom  and  hang  mouth  downwards,  so 
that  they  drain  dry  and  dust  does  not  settle  in  them. 
If  a  special  small  shelf  is  made  for  them,  it  should  either 
be  of  stout  wood  or  of  two-ply  material  so  as  to  avoid 
warping.  A  drip  board  may  be  placed  below. 

Q 


FIG.  3. 

Beaker  Rack.  This  consists  of  a  number  of  slats  of 
wood  arranged  to  form  V-shaped  troughs  open  at  the 
bottom,  and  with  one  side  wider  than  the  other.  The 
wider  side  of  the  trough  is  arranged  at  an  angle  of  about 
30°  with  the  horizontal,  the  shorter  side  being  at  right 
angles  with  the  other.  The  beakers  rest  in  the  troughs 


GENERAL   PROCEDURE  13 

with  their  sides  on  the  wider  side  of  the  trough  and  the  rim 
against  the  other  side.  In  this  way  they  drain  dry  and 
dust  does  not  collect  in  them.  A  hundred  beakers  can 
easily  be  kept  on  a  wall-space  measuring  4  ft.  by  4  ft., 
and  any  one  is  instantly  available  for  use. 


y 

/ 

>                < 

—  • 

>                < 

J   L 

FIG.  4. 


Rack  for  Flasks.  Flasks  are  conveniently  stored  in  a 
rack  consisting  of  two  battens  or  rods  of  wood  arranged 
parallel  to  one  another  at  such  a  distance  apart  that 
the  neck  of  the  flask  passes  between  them  and  the 
flask  hangs  supported  by  its  sides. 


7V7VY 


FIG.  5. 

Filtering  Stand.    A  stand  to  take  six  funnels  side  by 
side,  as  shown  in  the  sketch,  is  very  handy.    It  should 


14  MODERN   STEEL   ANALYSIS 

have  a  movable  shelf  below  the  funnel  stems  so  that 
filtration  into  beakers  of  different  depths  can  be  carried 
out. 

Burette  Stand.    Burettes  are  very  conveniently  sup- 
ported in  the  apparatus  shown,  which  consists  of  two 


FIG.  6. 

narrow  shelves,  the  lower  about  10  in.  and  the  other 
2  ft.  above  the  bench  level.  The  lower  shelf  has  notches 
a  little  wider  than  the  burettes  cut  in  it,  the  upper,  holes 
through  which  the  tops  of  the  burettes  pass.  The 
burettes  are  prevented  from  dropping  down  by  a  stout 
piece  of  rubber  sheet  slipped  over  them  as  shown  :  a 
cork  will  serve  equally  well. 


ALUMINIUM 

ALUMINIUM  is  occasionally  present  in  steels  derived 
from  the  ore  from  which  the  pig-iron  was  smelted,  but 
its  presence  is  more  frequently  due  to  the  addition  of 
aluminium  in  the  ladle.  It  is  chiefly  important  in  view 
of  its  action  in  producing  quiet  casts,  which  effect  is 
supposed  to  be  due  to  its  rapid  reduction  of  the  oxides 
present  without  elimination  of  gas. 

In  the  estimation  of  aluminium  in  steel  advantage  is 
usually  taken  of  the  insolubility  of  aluminium  phos- 
phate in  neutral  solutions,  ferrous  phosphate  being 
soluble.  The  estimation  of  very  small  amounts  of 
aluminium  with  accuracy  is  attended  with  some 
difficulty,  but  fortunately  the  importance  of  traces  of 
this  element  is  generally  considered  to  be  small. 

Estimation.  Dissolve  10  or  20  grm.  of  the  sample 
in  100  or  200  c.c.  of  hydrochloric  acid  (1 : 1).  Boil  the 
solution,  dilute  to  300  c.c.  and  pass  H2S  until  the  pre- 
cipitate, if  any,  flocks  together,  and  filter  off  any 
precipitated  copper  sulphide,  carbon,  and  silica.  Boil 
thoroughly  for  ten  minutes  and  add  25  c.c.  of  sodium 
phosphate  solution  (10  per  cent.),  followed  by  ammonia 
until  a  precipitate  just  forms  and  is  not  re-dissolved. 
Clear  the  solution  by  adding  2  c.c.  of  hydrochloric  acid, 
add  a  considerable  amount  of  acetic  acid,  dilute  to  about 
400  c.c.,  and  boil.  When  the  solution  has  boiled  remove 
it  from  the  plate  and  add  about  a  tablespoonful  of 

15 


1 6  MODERN   STEEL   ANALYSIS 

sodium  thiosulphate.  Boil  again  thoroughly  for  about 
ten  minutes,  allow  the  precipitate  to  settle,  and  filter. 
Wash  the  precipitate  thoroughly  with  hot  water  and 
ignite.  If  white  it  may  be  weighed  at  once  as  A1P04 ; 
if  not  white  it  may  be  redissolved  in  a  little  strong 
hydrochloric  acid,  the  iron  precipitated  by  boiling  with 
a  fair  excess  of  caustic  soda,  and  the  aluminium  re- 
precipitated  in  the  filtrate  exactly  as  before  after  adding 
10  c.c.  of  sodium  phosphate.  Al  in  A1P04  =  22-10  %. 

Chromium.  Chromium  if  present  will  follow  the 
aluminium  through  all  the  steps  of  the  preceding 
estimation.  It  may  be  separated  by  fusing  the  pre- 
cipitate in  a  platinum  dish  with  sodium  carbonate 
containing  a  very  little  sodium  peroxide.  On  dissolving 
the  melt  in  hot  water,  acidifying  with  sulphuric  acid, 
adding  a  little  more  sodium  phosphate,  and  then  making 
alkaline  with  ammonia,  aluminium  phosphate  is  precipi- 
tated while  chromium  remains  dissolved  as  ammonium 
chromate. 

Tungsten.  May  remain  undissolved  to  a  large 
extent.  Any  passing  into  solution  is  removed  by  the 
passage  of  sulphuretted  hydrogen. 

Molybdenum.  Is  removed  by  the  sulphuretted  hydrogen. 

Vanadium.  If  vanadium  be  present  in  the  precipitate 
the  procedure  given  above  under  chromium  may  be 
applied,  and  a  fairly  large  excess  of  phosphate  and 
ammonia  added. 

Titanium.  This  element  may  be  present  even  if  the 
precipitate  is  white.  The  precipitate  should  be  fused 
with  potassium  bisulphate,  the  melt  dissolved  in  dilute 
sulphuric  acid,  and  the  titanium  estimated  colori- 
metrically.  The  corresponding  weight  of  titanic  oxide, 
TiO,,  should  be  deducted. 


ARSENIC 

ARSENIC  occurs  in  nearly  all  varieties  of  steel,  and  is 
considered  to  have  a  similar  effect  to  phosphorus  on 
the  metal,  but  its  influence  is  less  marked.  The  follow- 
ing method  for  its  estimation  is  probably  the  simplest 
and  is  not  interfered  with  by  any  element  commonly 
occurring  in  steel. 

Estimation.  Weigh  5  grm.  of  the  sample  into  a 
500  c.c.  distilling  flask  fitted  with  a  rubber  stopper 
carrying  a  thermometer  graduated  to  120°  C.  Attach 
to  the  side  a  Will  and  Varrentrap  absorption  tube  filled 
with  bromine  water  and  about  2  c.c.  of  bromine  in 
addition.  Quickly  add  to  the  flask  60  c.c.  of  hot 
hydrochloric  acid  (1  : 1),  replace  the  thermometer,  and 
heat  gently  until  the  steel  is  all  dissolved  and  most  of 
the  bromine  in  the  absorption  tube  has  disappeared. 
Remove  the  flame  and  cool  somewhat.  Add  the 
contents  of  the  absorption  tube  to  the  flask  and  also 
100  c.c.  of  calcium  chloride  solution  (see  Appendix). 
Attach  to  the  side  tube  a  small  condenser  and  distil 
until  the  temperature  reaches  115°,  collecting  the 
distillate  in  a  conical  flask.  Remove  the  flame.  The 
arsenic,  which  has  been  evolved  as  arsenious  chloride 
and  is  present  in  the  receiver  as  arsenious  acid,  is  now 
estimated  by  means  of  iodine.  Add  to  the  receiver  an 
equal  volume  of  water  and  a  little  starch  solution  (see 

J7  2 


1  8  MODERN   STEEL  ANALYSIS 

Appendix  I),  and  run  in  from  a  burette  standard  centi- 
normal  iodine  solution  until  a  blue  coloration  is 
obtained.  The  percentage  of  arsenic  is  calculated  from 

N 
the  relation  1  c.c-r--r  iodine  =  "000375  grm.  As. 


A  little  arsenic  is  occasionally  present  in  the  reagents, 
and  in  consequence  a  blank  estimation  should  be  made, 
using  double  the  volume  of  reagents  and  the  same 
amount  of  steel. 

The  iodine  solution  should  be  standardized  against 
pure  arsenious  oxide  by  dissolving  about  0-1  grm.  in  a 
little  sodium  carbonate  solution,  acidifying  with  hydro- 
chloric acid,  and  titrating. 


CARBON 

THE  proportion  of  carbon  in  steel  has  such  a  far- 
reaching  influence  on  the  properties  of  the  metal  that 
it  is  natural  for  its  estimation  to  have  attracted  more 
notice  than  that  of  any  other  element.  New  methods 
still  continue  to  be  suggested  and  applied,  and  some  of 
these  will  be  considered  later.  The  methods  at  present 
most  widely  adopted  are ;  (1)  the  colour  comparison 
method ;  (2)  the  direct  combustion  method ;  (3)  the 
wet  combustion  method. 

Of  these  three  methods  the  first  is  the  simplest  and 
least  accurate,  while  the  second  and  third  are  the 
methods  relied  on  for  specification  purposes.  For  all 
ordinary  steels  the  estimation  of  carbon  by  direct  com- 
bustion in  a  current  of  oxygen  is  the  most  accurate 
method  known,  but  high  nickel  steels  are  only  burnt 
with  considerable  difficulty  unless  the  drillings  or 
turnings  are  very  thin  and  a  temperature  of  at  least 
1000°  C.  is  employed.  There  are  fewer  opportunities 
for  errors  to  creep  into  this  method  than  in  the  case  of 
the  wet  combustion  method,  and  if  a  blank  is  deter- 
mined before  and  after  a  series  of  estimations  and  the 
contents  of  the  boat  after  an  estimation  are  examined 
for  metallic  residue,  which  is  readily  done  by  crushing 
in  a  mortar,  it  is  quite  permissible  to  rely  firmly  on  the 
result.  In  the  wet  combustion  method,  by  which  is 

19 


20  MODERN   STEEL   ANALYSIS 

meant  the  method  depending  on  the  combustion  in  air 
or  oxygen  of  the  carbonaceous  residue  separated  from 
the  steel  by  solutions  of  double  copper  salts,  carbon 
present  in  the  steel  as  carbon  monoxide  and  carbon 
dioxide  is  completely  lost,  and  a  further  loss  may  occur 
through  the  formation  of  hydrocarbons  through  the 
action  of  the  solutions  on  the  steel.     Goutal  (Comptes 
Rendus,  CXLVIII,  1909,  p.  988)  has  found  that  in  certain 
cases  the  total  loss  from  these  causes  may  amount  to 
0-0435  per  cent.    Copper  potassium  chloride  is  to  be 
preferred  to  copper  ammonium  chloride  for  the  separa- 
tion, as  the  latter  may  introduce  a  positive  error  through 
the  presence  of  pyridine  hydrochloride,  which  is  some- 
times present.    Statements  that  dissolved  cellulose  is 
also  occasionally  present  have  been  made.    In  common 
practice  the  solution  is  made  up  from  copper  sulphate 
and    ammonium    chloride.    The    advantages    of    the 
method  are  simpler  apparatus  and  ability  to  use  air 
instead  of  oxygen.    By  suitable  arrangement  a  large 
number  of  samples  may  be  dealt  with  in  this  way 
almost  as  quickly  as  by  the  direct  process.    The  process 
depending  on  solution  of  the  steel  in  chromic  and 
sulphuric  acid  solution  containing  copper,  thus  oxidizing 
the  carbon  to  carbon  dioxide,  which  is  suitably  purified, 
absorbed,  and  weighed,  can  be  made  to  give  accurate 
results,  but  requires  more  manipulative  skill  and  takes 
considerably    more    time    and    attention.    The    glass 
apparatus  employed  in  the  estimation  is  usually  both 
expensive  and  fragile,  and  the  author  prefers  to  use 
this  method  only  for  check  estimations  in  the  case  of 
steels  which  are  burnt  with  difficulty,  e.g.  high  nickel 
and  nickel  chromium  steels. 


CARBON  21 

The  well-known  colour  comparison  method  depends 
on  the  fact  that  when  steel  is  dissolved  in  diluted  nitric 
acid  part  of  the  carbon  goes  into  solution,  forming  an 
orange-brown  liquid.  By  comparing  the  intensity  of 
the  colour  with  that  produced  by  a  steel  of  known  carbon 
content  an  estimate  of  the  amount  of  carbon  present 
can  be  made.  This  method  is  not  to  be  depended  on 
for  a  high  degree  of  accuracy  for  several  reasons.  In 
the  first  place  the  colour  developed  by  a  given  steel  is 
dependent  on  its  state  of  annealing — indeed  the  colour 
carbon  method  has  been  used  to  check  the  annealing  of 
samples — while  small  differences  in  the  composition 
of  the  standard  and  sample  can  produce  a  considerable 
difference  in  tint.  Copper  is  present  in  varying  amounts  in 
most  steels,  but  it  would  be  exceptional  for  its  influence 
in  this  estimation  to  be  allowed  for.  Very  large  errors 
also  may  be  introduced  even  when  annealing  is  perfect, 
and  the  samples  are  similar,  if  the  percentage  of  carbon 
in  the  two  is  not  approximately  the  same.  It  by  no 
means  follows  that  a  steel  containing  0-8  carbon  will 
yield  a  solution  of  twice  the  intensity  produced  by  a 
04  carbon  steel.  Nevertheless  the  simplicity  of  the 
operations  and  the  ease  with  which  a  number  of  deter- 
minations can  be  made  give  the  process  considerable 
value  where  its  limitations  are  well  understood. 

Stead's  modification  of  the  test,  which  consists  in 
precipitating  the  iron  and  other  metals  with  caustic 
soda  and  comparing  the  more  intensely  coloured 
filtrates,  eliminates  a  good  many  of  these  disadvantages 
and  is  more  accurate,  though  slightly  more  troublesome. 
Colorimetric  Estimation.  The  estimation  is  carried 
out  as  follows  :  Exactly  0-1  grm.  of  the  sample  and 


22  MODERN   STEEL   ANALYSIS 

(M  grm.  of  a  standard  steel  containing  about  the 
expected  percentage  of  carbon  are  weighed  into  test- 
tubes.  To  each  tube  is  added  2  c.c.  of  nitric  acid  (1*2) 
and  the  test-tubes  are  placed  in  a  bath  of  boiling  water 
— a  beaker  serves  very  well — for  twenty  minutes.  The 
tubes  are  then  removed  and  cooled  together  in  another 
beaker  of  cold  water.  For  the  purpose  of  comparing 
the  intensity  of  the  colour,  special  tubes  of  similar  shape 
and  capacity  are  used.  The  standard  solution  is  made 
up  to  100,  200,  or  more  times  as  many  c.c.  as  it  contains 
per  cent,  of  carbon  and  transferred  to  one  of  the  com- 
parison tubes.  Thus  a  steel  containing  0'15  per  cent. 
of  carbon  would  be  made  up  to  15  or  30  c.c.  The 
sample  is  then  washed  into  another  comparison  tube 
and  diluted  until  its  colour  is  equal  to  that  of  the 
standard.  The  tubes  are  most  readily  matched  by 
holding  them  side  by  side  in  an  inclined  position  on  a 
white  tile  and  looking  through  them.  When  the 
colours  are  nearly  the  same  the  left  hand  tube  should 
be  changed  over  to  the  right  hand  and  back  again  to 
eliminate  chance  differences  in  lighting.  The  volume 
of  the  sample  is  then  measured  and  the  number  of 
cubic  centimetres,  divided  by  100,  or  200,  gives  the 
percentage  of  carbon. 

Estimation  by  Direct  Combustion.  This  is  carried 
out  in  the  apparatus  shown  in  Fig.  7.  Oxygen  from  a 
cylinder  is  passed  through  A,  which  must  be  provided 
with  a  clip  or  tap,  into  the  gasholder,  B,  whence  it 
passes  through  the  purifying  tubes,  C  and  D,  containing 
strong  sulphuric  acid  and  soda  lime  respectively.  Joints 
between  different  pieces  of  the  apparatus  are  made 
with  pressure  tubing  as  this  lasts  very  much  longer 


CARBON 

than  thin- walled  tubing  without  crack- 
ing or  leaking.  The  combustion  tube, 
I,  which  is  of  porcelain  or  silica  about 
1  in.  in  internal  diameter,  is  connected 
to  D  by  a  few  inches  of  rubber  tube, 
E,  through  the  tap,  F,  and  is  closed 
at  either  end  by  well-fitting  single- 
holed  rubber  stoppers.  The  tube  is 
laid  in  a  furnace  capable  of  attaining 
an  orange-red  heat  which  may  be 
heated  by  gas  or  by  electrical  resistance. 
An  electric  resistance  furnace  is  to  be 
preferred  to  a  gas-fired  furnace  largely 
because  of  the  easy  attainment  of 
temperatures  not  readily  reached  in  a 
gas  furnace  and  also  in  view  of  its 
cleanness.  Gas  furnaces  also  have  the 
disadvantage  that  they  make  the 
laboratory  very  hot,  besides  intro- 
ducing a  large  quantity  of  carbon 
dioxide  into  the  atmosphere,  which 
is  most  undesirable.  Silica  tubes 
have  been  used  to  replace  the  porce- 
lain, but  their  much  higher  price 
is  not  compensated  by  a  greatly  in- 
creased life.  The  porcelain  tube  is 
packed  from  the  middle  to  near  the 
exit  end  with  coarse  copper  oxide 
(from  wire)  between  plugs  of 
ignited  asbestos.  If  a  silica  tube 
is  used  it  must  be  packed  with 
platinized  quartz.  To  guard  the 


24  MODERN   STEEL   ANALYSIS 

stoppers  from  the  effects  of  the  heat  two  compact 
rolls  of  ignited  copper  gauze,  occupying  nearly 
the  whole  bore  of  the  tube,  are  inserted,  one 
near  the  exit  end,  the  other  at  the  entrance.  The 
exit  end  of  the  tube  is  connected  with  the  U  tube, 
H,  which  is  packed  with  small  pieces  of  pumice.  This 
is  fitted  into  a  reservoir,  consisting  of  a  small  wide- 
mouthed  bottle,  N,  closed  by  a  two-holed  rubber  stopper 
through  the  other  hole  of  which  passes  a  tube  with  a 
tap,  or  rubber  extension  and  clip.  This  reservoir 
contains  a  mixture  of  sulphuric  acid  and  potassium 
dichromate,  which  is  occasionally  forced  up  over  the 
pumice  by  blowing  down  the  tap-tube  and  allowed  to 
subside  again.  The  pumice  is  by  this  means  kept 
continually  moistened  with  fresh  acid  and  efficiently 
dries  the  gases  passing  through  it,  while  at  the  same 
time  eliminating  sulphur  dioxide  and  trioxide.  The 
carbon  dioxide  is  absorbed  in  the  stoppered  weighing 
tube,  J,  the  left  hand  limb  of  which  is  packed  with 
soda  lime  or  coarsely  powdered  caustic  soda,  the  other 
containing  calcium  chloride.  The  safety  wash-bottle, 
L,  contains  potash  solution,  and  K  is  a  guard  tube  filled 
with  calcium  chloride. 

To  carry  out  the  determination  a  supply  of  oxygen 
is  passed  into  A,  tap  F  closed,  and  the  furnace  heated 
to  a  bright  red.  About  1000°  C.  is  the  right  tempera- 
ture. The  weighing  tube,  rilled  with  oxygen,  is  attached 
and  a  blank  determination  carried  out  by  passing  a 
stream  of  oxygen  for  half  an  hour.  The  flow  of  gas  is 
regulated  by  one  of  the  taps  on  the  weighing  tube, 
and  the  bubbles  should  succeed  one  another  in  the 
safety  wash-bottle,  L,  without  an  appreciable  pause. 


CARBON  25 

If  the  blank  is  satisfactory — it  should  be  zero — 2-727 
grm.  of  the  sample,  sifted  through  a  30-mesh  sieve, 
or  5454  if  the  carbon  is  under  0-2  per  cent,  are  weighed 
into  a  small  stoppered  weighing  bottle  containing  about 
1  grm.  of  ignited  alumina,  shaken  up,  and  transferred 
to  the  combustion  boat.  The  object  of  the  alumina  is 
to  prevent  globules  of  oxide  forming  round  unburnt 
steel  and  preventing  complete  combustion.  Red  lead, 
bismuth  trioxide,  and  other  oxygen-containing  materials 
have  been  recommended,  but  are  unnecessary  if  the 
temperature  of  the  furnace  is  high  enough,  except  in 
the  case  of  some  chromium  steels.  These  materials 
also  usually  introduce  a  blank.  The  combustion  boat 
should  be  capacious  and  of  porcelain,  fire-clay,  or 
alundum.  If  made  of  porcelain,  it  must  be  covered 
internally  with  a  coating  of  thin  wet  asbestos  paper 
and  thoroughly  ignited  in  a  muffle.  If  this  precaution 
is  not  taken  a  new  boat  will  probably  be  necessary  for 
each  combustion,  since  glazed  porcelain  is  attacked  by 
the  oxide,  which  also  adheres  so  firmly  as  only  to  be 
removed  with  great  difficulty  without  breaking  the 
boat.  Alundum  boats  are  very  satisfactory,  especially 
when  used  with  the  specially  prepared  alumina  which 
the  makers  supply.  The  boat  and  contents  are  now 
quickly  inserted  into  the  heated  combustion  tube, 
pushed  up  into  the  hot  part,  the  protective  screen  of 
copper  gauze  placed  in  position,  and  the  stopper 
replaced.  The  oxygen  supply  is  turned  on  through  the 
tap,  H,  and  the  stream  regulated  as  before.  By  this 
means  the  whole  apparatus  as  far  as  the  tap  on  the 
weighing  tube  is  kept  under  a  slight  positive  pressure 
of  oxygen  and  the  drillings  are  automatically  supplied 


26  MODERN    STEEL   ANALYSIS 

with  as  much  oxygen  as  they  require,  while  there  is 
no  possibility  of  "  sucking  back."  Oxygen  from  the 
cylinder  may  be  passed  meanwhile  into  the  reservoir 
to  replace  that  used  up.  The  apparatus  needs  no 
watching,  and  after  thirty  minutes  the  weighing  tube 
is  removed  and  re-weighed.  It  may  be  re-attached  for 
a  further  period,  but  seldom  increases  further  in  weight. 
The  increase  in  weight  multiplied  by  10  or  5  corresponds 
to  the  percentage  of  carbon,  if  2-727  grm.  or  5-454  grm. 
respectively  were  taken.  The  combustion  boat  is  then 
drawn  out  of  the  tube  and  its  contents  quickly  shaken 
out,  another  boat  being  introduced  and  the  next  deter- 
mination made. 

Special  Steels.  Where  a  steel  is  only  burnt  with 
difficulty  under  the  above  conditions,  the  aid  of  red 
lead  must  be  called  in  to  ensure  complete  combustion. 
The  sample  is  shaken  with  a  weighed  quantity  of  red 
lead,  in  place  of  the  alumina,  in  a  weighing  bottle  before 
placing  in  the  boat.  A  covering  of  asbestos  in  this 
case  is  essential,  as  otherwise  the  litharge  formed  will 
creep  over  the  edges  of  the  boat  and  damage  the  tube. 
A  blank  determination  with  red  lead  only  present  must 
be  carried  out,  but  with  good  samples  this  is  very 
low. 

The  Wet  Combustion  Method.  The  method  de- 
pends on  first  separating  the  carbonaceous  constituents 
from  the  iron  by  solutions  of  copper  salts  and  after- 
wards burning  the  residue. 

A  solution  containing  250  grm.  crystallized  copper 
sulphate  and  100  grm.  pure  ammonium  chloride  per 
litre  is  prepared.  The  drillings  are  weighed  out  in 
5-454  grm.  lots  into  marked  conical  flasks  and  then 


CARBON  27 

80  c.c.  of  the  solution  are  added  to  each.  The  flasks 
are  shaken  round  well  and  allowed  to  stand  overnight. 
In  the  morning  the  residual  copper  is  brought  into 
solution  by  adding  20  c.c.  of  hydrochloric  acid  to  each 
and  warming  to  about  50°  C.  with  occasional  shaking. 
The  carbon  is  then  filtered  off  through  ignited  asbestos 
and  washed  with  hot  water.  The  filter  pad  is  carefully 
lifted  out  and  placed  in  a  marked  combustion  boat,  the 
sides  of  the  funnel  being  carefully  cleaned  by  wiping  with 


FIG.  8. 


small  pads  of  ignited  asbestos,  and  these  are  also  added 
to  the  boat.  The  whole  is  now  dried  in  a  steam  or 
air  oven  at  about  100°  C.  When  dry  it  is  transferred 
to  the  combustion  tube,  which  is  shown  in  Fig.  8. 
This  apparatus  is  similar  in  most  respects  to  that  used 
in  the  direct  combustion  method,  but  oxygen  is  un- 
necessary. Air  is  drawn  through  the  apparatus  at  a 
suitable  rate  by  the  aspirator,  G.  No  other  purification 
of  the  entering  air  is  necessary  beyond  bubbling  through 
a  strong  solution  of  potash  in  the  washer,  A.  To  the 
other  end  of  the  combustion  tube  are  attached  a  drying 
tube,  C,  containing  pumice  moistened  with  sulphuric 
and  chromic  acids,  the  weighing  tube,  D,  filled  in  the 


28  MODERN   STEEL   ANALYSIS 

same  way  as  for  the  estimation  by  direct  combustion, 
and  a  guard  tube,  E,  of  calcium  chloride.  The  com- 
bustion of  the  carbonaceous  matter  is  generally  complete 
in  less  than  half  an  hour. 

Of  other  methods  for  the  estimation  of  carbon,  Wiist's 
method  as  used  by  Stadeler  (Metallurgie,  VIII,  p.  268) 
consists  in  burning  about  half  a  gram  of  the  steel  mixed 
with  five  times  its  weight  of  an  alloy  of  antimony  3, 
tin  1,  in  oxygen  at  900°  C.,  and  is  stated  to  be  very 
useful  with  refractory  alloys.  Goutal  (Revue  de  Met., 
1911,  VIII,  p.  391)  burns  in  a  calorimetric  bomb  in 
compressed  oxygen,  absorbing  the  carbon  dioxide  in 
baryta  and  titrating  the  excess  of  alkali  with  acid  and 
phenol  phthalein,  but  neither  of  these  methods  is  likely 
to  find  a  wide  technical  application. 


CHROMIUM 

CHROMIUM  occurs  in  traces  in  many  steels  and  irons 
accidentally,  owing  to  its  presence  in  the  ores,  and  is 
also  added  purposely  to  many  special  steels,  particu- 
larly armour-plate  and  high-speed  steels.  It  may  be 
estimated  gravimetrically  as  chromium  phosphate,  but 
the  volumetric  estimation  depending  on  the  oxidizing 
properties  of  chromic  acid  is  more  convenient  and 
generally  more  accurate.  Where  traces  of  chromium 
only  are  present,  it  is  best  to  separate  all  the  chromium 
first  as  phosphate  and  then  estimate  volumetrically  after 
conversion  into  chromic  acid. 

Qualitative  Detection.  If  chromium  is  present  to  the 
extent  of  0-5  per  cent,  or  more  in  a  steel,  the  solution 
in  dilute  sulphuric  acid  will  have  a  pronounced  green 
colour,  the  solution  of  a  plain  steel  being  practically 
colourless.  Nickel  produces  the  same  effect  in  a  much 
less  marked  degree. 

Gravimetric  Estimation.  Dissolve  2  grm.  of  the 
steel  in  40  c.c.  hydrochloric  acid  (1:1)  and  dilute  to 
200  c.c.  Heat  the  solution  and  nearly  neutralize  it  with 
sodium  carbonate.  When  only  feebly  acid,  add  20  c.c. 
of  10  per  cent,  sodium  phosphate  and  10  grm.  of  sodium 
thiosulphate.  Boil  well  and  allow  to  settle.  Filter 
through  a  close  filter  and  wash  with  5  per  cent,  am- 
monium nitrate  solution.  Re-dissolve  in  hydrochloric 

29 


30  MODERN    STEEL   ANALYSIS 

acid  and  repeat  the  precipitation  as  before.  The 
precipitate  will  then  be  free  from  iron  and  manganese, 
but  will  contain  aluminium,  copper,  and  nickel  if  present. 
If  absent,  ignite  and  weigh  as  chromium  phosphate 
containing  40-94  per  cent.  Cr.  The  same  excess  of 
sodium  phosphate  should  be  added  in  the  second  pre- 
cipitation, otherwise  a  precipitate  of  uncertain  com- 
position will  result.  If  the  above  metals  are  present 
the  precipitate  must  be  fused  with  sodium  carbonate, 
extracted  with  water  and  filtered.  Aluminium  and 
chromium  are  present  in  the  nitrate.  Acidify  with 
dilute  HC1  and  add  dilute  ammonia  to  precipitate  the 
aluminium.  Filter,  acidify,  reduce  the  chromic  acid 
with  sulphurous  acid,  and  precipitate  as  above.  This 
method  should  only  be  used  for  small  amounts,  0-2  per 
cent,  and  less,  of  chromium,  and  even  in  this  case  it  is 
better  to  fuse  the  precipitate  with  sodium  carbonate 
and  titrate  the  chromic  acid  resulting. 

Volumetric  Estimation.  Weigh  2  grm.  of  the  sample 
into  a  600  c.c.  long  beaker  and  add  30  c.c.  of  water, 
followed  by  15  c.c.  strong  sulphuric  acid.  Dissolve 
with  the  aid  of  gentle  heat  on  the  hot  plate  with  the 
cover  on.  The  speed  of  solution  varies  considerably 
with  different  samples,  and  may  even  take  some  hours. 
Crystals  of  ferrous  sulphate  should  be  re-dissolved  with 
a  little  water  if  they  form,  otherwise  solution  will  be 
much  retarded.  When  all  is  dissolved  except  a  few 
floating  black  specks,  add  1-2  nitric  acid  drop  by  drop 
from  a  pipette  until  all  the  iron  is  oxidized,  and  boil  off 
nitrous  fumes.  Add  200  c.c.  of  hot  water  and  then 
7  c.c.  of  3  per  cent,  potassium  permanganate  solution 
and  a  small  piece  of  firebrick  about  the  size  of  a  pea  to 


CHROMIUM  31 

prevent  bumping.  Boil  for  fifteen  minutes.  A  pre- 
cipitate of  manganese  dioxide  should  remain.  Now 
add  50  c.c.  of  dilute  hydrochloric  acid  (30  c.c.  strong 
acid  per  100  c.c.)  and  boil  till  the  precipitate  just 
clears  up.  Dilute  at  once  with  hot  water  to  400  c.c. 
and  boil  rapidly  for  half  an  hour,  adding  water  if 
necessary  to  prevent  the  volume  falling  below  350  c.c. 
Allow  to  cool  completely,  add  a  slight  excess  of  ferrous 
sulphate  and  titrate  back  with  standard  bichromate 
solution  (1  c.c.  =-001  Cr. — see  Appendix  I).  The  number 
of  cubic  centimetres  of  bichromate  equivalent  to  the 
total  ferrous  sulphate  added,  less  the  amount  taken  up 
in  the  back  titration,  divided  by  20,  represents  the 
percentage  of  chromium  in  the  sample. 

Rapid  Volumetric  Estimation.  The  following 
method — due  to  Gregory  (Journ.  Chem.  Soc.,  1907, 
p.  1847) — gives  accurate  results  and  takes  less  than  an 
hour. 

Dissolve  2  grm.  of  the  steel  in  as  little  1-2  nitric  acid 
as  possible,  dilute  to  50  c.c.,  add  1  grm.  of  silver  nitrate 
and  10  grm.  of  ammonium  persulphate  and  boil  for  a 
few  minutes.  Ammonium  chloride  (-25  grm.  or  2'5  c.c. 
of  10  per  cent,  solution)  is  added — the  quantity  being 
insufficient  to  precipitate  the  whole  of  the  silver  nitrate 
— and  the  solution  boiled,  when  the  permanganate  is 
destroyed  and  the  manganese  partly  precipitated  as 
hydrated  oxide  and  partly  converted  into  manganous 
chloride.  The  solution  is  filtered  through  asbestos  after 
making  up  to  a  definite  volume,  and  an  aliquot  part 
titrated  with  ferrous  sulphate  and  standard  bichromate. 
The  presence  of  free  silver  nitrate  throughout  the 
estimation  ensures  the  absence  of  free  chlorine. 


32  MODERN   STEEL   ANALYSIS 

Vanadium.  In  the  volumetric  estimation  vanadium 
only  interferes  by  oxidizing  part  of  the  excess  of  ferrous 
sulphate  added.  On  subsequently  titrating  back  with 
bichromate  an  uncertain  end  point  is  obtained  before 
enough  has  been  added  to  oxidize  the  excess  of  ferrous 
sulphate  present.  If  the  back  titration  is  carried  out 
with  permanganate  and  the  end  point  taken  as  reached 
when  a  slight  pink  colour  does  not  disappear  in  half  a 
minute,  the  interference  of  the  vanadium  is  avoided 
as  the  hypovanadate  is  re-oxidized  by  the  perman- 
ganate to  exactly  the  same  extent  as  it  was  produced 
by  the  ferrous  sulphate. 

Molybdenum  and  Titanium.  These  elements  do  not 
interfere  with  the  volumetric  estimation. 

Tungsten.  If  the  sample  dissolves  but  leaves  a 
residue  of  tungstic  oxide,  this  should  be  filtered  off 
after  oxidizing  the  iron  with  nitric  acid.  If  great 
difficulty  in  effecting  solution  is  encountered,  dissolve 
the  sample  in  hydrochloric  acid  with  a  little  nitric  acid 
(see  Tungsten,  p.  92),  afterwards  diluting  and  separating 
the  tungstic  oxide.  Add  to  the  filtrate  15  c.c.  of  strong 
sulphuric  acid  and  evaporate  till  fumes  are  freely 
evolved.  Cool,  dilute,  add  permanganate,  and  proceed 
as  in  the  ordinary  volumetric  estimation,  adding  if 
necessary  a  little  more  permanganate. 


COBALT 

COBALT  is  one  of  the  most  recent  additions  to  the 
ranks  of  elements  specially  added  to  high-speed  steels. 
Its  estimation  has  in  consequence  not  so  far  received 
very  much  attention,  but  the  following  methods  have 
been  found  by  the  author  to  work  well. 

Cyanometric  Estimation.    This  is  carried  out  in  the 
same  way  as  for  nickel  until  the  iron  has  been  separated 
and  the  500  c.c.  of  solution  for  the  titration  obtained. 
At  this  point  it  is  desirable  to  add  50  c.c.  of  20  per  cent, 
ammonium  sulphate  solution,  as  it  improves  the  colour 
of  the  solution  and  adds  to  the  sharpness  of  the  end 
point.    This  is  slightly  more  difficult  to  see  than  in  the 
case  of  nickel,  as  the  turbidity  appears  more  slowly, 
and  different  operators  are  liable  to  take  slightly  different 
points.    For  this  reason  a  standard  cobalt  solution 
containing  about   the   same  amount   as  the   sample 
should  be  added  to  a  solution  of  a  cobalt-  (and  nickel-) 
free  steel  and  the  potassium  cyanide  standardized  by 
carrying  through  the  estimation  in  exactly  the  same 
way.     One  atom  of  cobalt  is,  roughly,  equivalent  to 
five    molecules   of   potassium   cyanide.      A  standard 
solution    of   cobalt  is   prepared  by  dissolving  about 
the    right     quantity    of    any    pure    cobalt    salt    in 
1   litre   of   water,  evaporating    an    aliquot    part    to 
dryness  with    slight    excess  of  sulphuric   acid  in  a 

33  3 


34  MODERN    STEEL   ANALYSIS 

tared  dish,  heating  just  to  dull  redness,  and  weighing 
as  CoS04. 

Gravimetric  Estimation.  The  estimation  of  cobalt 
in  high-speed  steels  is  best  carried  out  as  follows.  Five 
grams,  or  less,  of  the  steel  are  weighed  and  dissolved 
in  80  c.c.  strong  hydrochloric  acid  as  far  as  possible. 
Strong  nitric  acid  is  then  added  in  just  sufficient  quan- 
tity to  dissolve  the  iron  and  effect  solution.  The  solu- 
tion is  then  evaporated  until  tungstic  oxide  begins  to 
separate,  diluted  with  80  c.c.  of  hot  water,  and  boiled. 
The  tungstic  oxide  is  filtered  off  and  the  solution  diluted 
to  about  200  c.c.  with  hot  water.  Ammonium  carbonate 
is  now  added  until  a  permanent  precipitate  is  just 
formed,  which  is  cleared  up  by  adding  lU-15  c.c.  acetic 
acid.  The  solution  is  then  diluted  to  nearly  500  c.c. 
and  heated  to  boiling.  Ammonium  acetate  solution 
(see  Appendix  I)  is  added  to  the  extent  of  1  c.c.  per  gram 
of  steel  and  the  solution  just  boiled,  made  up  exactly  to 
500  c.c.  at  the  boiling  temperature,  and  250  c.c.  filtered 
off.  To  the  filtrate,  which  must  be  free  from  iron, 
10  grm.  of  ammonium  chloride  are  added  and  then 
ammonia  till  feebly  alkaline.  Sulphuretted  hydrogen 
is  now  passed  for  about  ten  minutes  until  all  cobalt, 
and  nickel  if  present,  is  precipitated  as  sulphide  together 
with  a  small  quantity  of  manganese  if  much  was  origi- 
nally present.  The  precipitate  is  allowed  to  settle, 
filtered  off  on  pulp,  and  then  washed  with  2-3  per  cent, 
acetic  acid  containing  sulphuretted  hydrogen,  which 
removes  practically  all  the  manganese  sulphide.  The 
precipitate  is  now  ignited,  and  if  cobalt  only  is  present, 
may  be  converted  into  cobalt  sulphate  by  moistening 
with  strong  nitric  acid  and  a  few  drops  of  sulphuric  acid 


COBALT  35 

in  a  tared  dish.  This  is  then  evaporated  to  dryness, 
the  sulphuric  acid  carefully  driven  off  by  heating  just 
to  dull  redness  and  weighed  as  CoS04  containing  38-04 
per  cent,  of  cobalt. 

If  nickel  is  also  present  the  precipitate  is  ignited  and 
dissolved  in  nitric  acid  and  taken  to  fumes  with  a  small 
quantity  of  sulphuric  acid  as  before,  and  is  then  dissolved 
in  about  50  c.c.  of  water.  Ammonium  sulphate  (10  c.c. 
of  30  per  cent.),  100  c.c.  1  :  1  ammonia,  and  100  c.c.  of 
water  are  added  and  the  solution  electrolysed  between 
platinum  electrodes  in  a  beaker.  A  current  density  of 
about  0*6  ampere  per  100  sq.  cm.  of  cathode  surface  at 
3  volts  is  necessary,  and  precipitation  is  complete  in 
about  four  hours.  A  trace  of  Mn02,  if  manganese  has 
not  been  completely  eliminated,  may  separate  towards 
the  end  of  the  electrolysis  but  will  not  interfere.  The 
precipitated  cobalt  and  nickel  are  weighed  together, 
dissolved  in  a  little  nitric  acid,  and  taken  to  dryness 
with  excess  of  hydrochloric  acid.  They  are  then  dis- 
solved in  100  c.c.  of  water  faintly  acidified  with  HC1 
per  0*1  grm.  of  metals.  The  solution  is  neutralized  with 
ammonia,  acidified  with  one  drop  of  HC1,  heated  to 
60°  or  70°,  and  the  nickel  precipitated  by  adding  slight 
excess  of  a  1  per  cent,  alcoholic  solution  of  dimethyl- 
glyoxime.  Ammonia  is  then  added  just  to  alkalinity, 
the  precipitate  filtered  off,  washed  with  hot  water,  dried, 
and  either  weighed  as  C4H1404N4Ni  containing  20*31 
per  cent.  Ni  or  ignited  at  the  mouth  of  the  muffle  and 
weighed  as  oxide  NiO,  cobalt  being  estimated  by 
difference. 


COPPER 

COPPER,  although  seldom  intentionally  added  to 
steel,  is  usually  present  in  small  and  varying  amounts. 
If  present  in  fair  quantity  it  may  be  detected  by  dis- 
solving the  steel  in  nitric  acid,  adding  dilute  ammonia, 
and  filtering,  when  the  nitrate  is  coloured  blue.  Nickel 
and  cobalt  both  interfere  with  the  test,  and  it  is  of  no 
great  sensitiveness.  If  traces  only  are  being  looked  for 
it  is  better  to  carry  through  an  estimation. 

Estimation.  Weigh  10  grm.  of  steel  into  a  600  c.c. 
beaker,  add  75  c.c.  of  water  and  then  25  c.c.  of  strong 
sulphuric  acid,  and  heat  gently  till  all  is  dissolved. 
Dilute  to  about  400  c.c.  with  hot  water  and  add  10  grm. 
of  sodium  thiosulphate.  Boil  the  solution  until  the 
precipitated  sulphur  clears  up,  and  filter  through  pulp. 
The  precipitate  consists  of  cuprous  sulphide,  together 
with  the  sulphides  of  antimony,  arsenic,  and  molyb- 
denum if  present,  and  also  possibly  the  oxides  of 
aluminium,  silicon,  chromium,  and  iron.  The  simplest 
way  to  estimate  the  copper  in  the  mixture  is  to  dissolve 
the  precipitate  as  far  as  possible  in  a  little  1*20  nitric 
acid  and  estimate  the  copper  colorimetrically  after 
addition  of  ammonia,  and  nitration  if  necessary,  by 
comparison  in  colour  carbon  tubes  with  a  standard 
copper  solution.  An  alternative  method  of  dealing 
with  the  precipitate  is  the  following  :  Ignite  and  weigh 

36 


COPPER  37 

the  precipitate,  transfer  it  to  a  small  beaker,  dissolve 
as  far  as  possible  in  10  c.c.  strong  hydrochloric  acid, 
dilute,  and  add  ammonia  till  alkaline.  Filter  off,  wash, 
and  ignite  the  precipitate  and  subtract  its  weight  from 
the  previous  weight.  The  difference  may  be  taken  as 
representing  the  weight  of  cuprous  sulphide,  which 
multiplied  by  0-798  gives  the  weight  of  copper  present, 
but  this  assumption  is  liable  to  grave  inaccuracy  if 
arsenic,  tin,  and  particularly  molybdenum  are  present. 
Tungsten.  This  is  the  only  element  which  interferes 
seriously  with  the  colorimetric  method  given  above.  If 
present  the  estimation  is  much  more  laborious,  but 
may  be  carried  out  as  follows  :  Dissolve  10  grm.  of  the 
sample  in  50  c.c.  strong  hydrochloric  acid,  and  when 
the  reaction  slackens  add  drop  by  drop  just  enough 
strong  nitric  acid  to  produce  a  clear  solution.  Evapo- 
rate till  a  precipitate  commences  to  form,  then  dilute 
with  100  c.c.  hot  water  and  boil.  Filter  off  the  pre- 
cipitated tungstic  acid  and  silica.  Add  a  considerable 
amount  of  sulphurous  acid  and  boil  off  the  excess. 
Treat  the  warm  solution  with  a  rapid  stream  of 
sulphuretted  hydrogen  until  the  precipitate  of  copper 
sulphide  becomes  dense  and  settles  readily.  Filter  and 
wash  the  precipitate  alternately  with  water  containing 
sulphuretted  hydrogen  and  5  per  cent,  hydrochloric 
acid.  Dissolve  the  precipitate  off  the  paper  with  hot 
1-20  nitric  acid,  perforate  the  filter,  and  wash  through 
any  residual  sulphur.  Boil  until  the  solution  is  clear. 
The  estimation  may  now  be  finished  by  the  colorimetric 
method  after  adding  ammonia,  or  the  copper  may  be 
estimated  iodimetrically  in  the  following  way  :  Add 
caustic  soda  or  sodium  carbonate  to  the  thoroughly 


38  MODERN   STEEL  ANALYSIS 

boiled  nitric  acid  solution  till  a  permanent  precipitate 
is  produced.  Re-dissolve  this  with  a  few  drops  of  acetic 
acid,  cool,  add  about  1  grm.  of  potassium  iodide  dis- 
solved in  a  little  water,  and  titrate  the  liberated  iodine 
with  standard  thiosulphate  (see  Appendix  I)  after  adding 
starch  solution. 


HYDROGEN 

HYDROGEN  occurs  in  appreciable  amounts  in  practically 
all  steels  and  irons,  electrolytic  steel  being  stated  to 
contain  sometimes  many  times  its  own  volume.  The 
presence  of  hydrogen  is  most  clearly  demonstrated  by 
heating  the  drillings  in  vacuo,  after  maintaining  them 
in  vacuo  with  a  drying  agent  for  long  enough  to  remove 
all  moisture,  and  analysing  the  gases  given  off.  On 
account  of  the  very  low  density  of  hydrogen  the  per- 
centage by  weight  is  very  small,  even  when  considerable 
volumes  of  hydrogen  are  obtained  as  above.  Thus  if  a 
steel  yield  its  own  volume  of  hydrogen  the  percentage 
by  weight  indicated  is  only  slightly  over  0-001 .  It  is 
exceedingly  unlikely  that  such  a  small  proportion  of 
any  element  can  have  much  injurious  influence  on  the 
quality  of  the  steel,  but  in  view  of  the  accusations 
which  have  been  brought  against  this  element,  and 
also  for  the  sake  of  completeness,  the  following  method 
of  estimation  is  given. 

Estimation.  The  determination  of  hydrogen  is  carried 
out  by  burning  the  steel  in  dry  oxygen  and  weighing 
the  water  formed. 

A  silica  combustion  tube,  similar  to  that  used  in  the 
estimation  of  carbon  by  direct  combustion,  is  fitted 
with  two  tight  one-hole  rubber  stoppers  and  placed  in 
a  furnace  capable  of  attaining  a  temperature  of  at  least 

39 


40  MODERN   STEEL   ANALYSIS 

900°  C.    The  steel — 50  grm.  or  even  more — is  weighed 
out,    mixed   with   a   little   recently   ignited   alumina, 
which  must  be  stored  in  a  good  desiccator,  and  intro- 
duced into  the  combustion  tube  in  recently  ignited 
boats  similar  to  those  used  in  the  estimation  of  carbon. 
A  supply  of  oxygen  from  a  cylinder,  purified  in  the 
same  way  as  for  carbon  determination,  but  passing 
through  a  drying  tube   of  phosphorus   pentoxide  in 
addition,  is  put  in  connection  with  the  tube,  a  glass  tap 
on  capillary  tube   being  placed  close  to  the  rubber 
stopper.    Arrangement   must   also   be   made   for   the 
supply  of  pure  dried  air.    The  rubber  stopper  at  the 
other  end  carries  a  wide  glass  tube  about  J  in.  in  diameter, 
and  to  this  is  connected  by  close-fitting  pressure  tubing 
the  weighing  tube.    The  weighing  tube  consists  of  a 
straight  tube,  about  \  in.  in  diameter,  terminating  at 
either  end  in  tubes  about  J  in.  in  diameter  and  \  in. 
long,  and  during  weighing  is  protected  by  small  glass 
caps  which  slip  over  the  open  ends  with  as  little  clear- 
ance as  possible.    It  is  filled  with  phosphorus  pentoxide 
after  first  pushing  a  small  plug  of  glass  wool  down  to 
the  end  of  the  wide  part  remote  from  the  furnace,  but 
the  end  close  to  the  furnace  must  not  contain  glass 
wool.    A  guard  tube  of  phosphorus  pentoxide,  consisting 
of  a  U-tube  with  side  arms  and  with  the  wide  openings 
of  the  limbs  sealed  off,  is  attached  after  the  weighing  tube. 
The  estimation  is  carried  out  as  follows  :  The  sample 
is  placed  in  the  combustion  tube,  which  is  then  swept 
out  for  five  minutes  with  pure  dried  air.    The  tap  on 
the  entrance  tube  is  then  closed  and  the  combustion  tube, 
weighing  tube,  and  guard  tube  evacuated  by  means 
of  a  Fleuss  or  other  pump  attached  to  the  guard  tube 


HYDROGEN  41 

until  the  pressure  is  reduced  well  below  1  mm.  of 
mercury.  The  apparatus  is  allowed  to  stand  empty 
for  half  an  hour,  at  the  end  of  which  time  it  is  examined 
for  leaks,  which  are  readily  shown  by  a  manometer. 
If  none  are  present,  the  apparatus  is  rilled  again  with 
dry  air  and  the  same  process  repeated  twice.  This 
step  completely  removes  moisture  from  the  drillings 
and  apparatus,  which  is  absolutely  essential.  The 
author  is  unaware  of  any  other  method  of  satisfactorily 
accomplishing  this  end,  mere  passage  of  a  current  of 
dry  gas  for  long  periods  being  quite  ineffectual.  The 
tube  is  now  allowed  to  fill  up  with  air,  the  guard  tube 
removed,  and  the  cap  placed  on  the  adjacent  end  of  the 
weighing  tube  while  the  current  is  still  passing.  The 
weighing  tube  is  then  disconnected  and  the  other  cap 
quickly  attached.  The  tube  issuing  from  the  com- 
bustion tube  is  closed  with  a  rubber  cap  while  the  gas 
is  still  issuing,  and  the  current  of  air  then  stopped.  The 
weighing  tube  is  then  carefully  polished  with  chamois 
leather,  weighed,  and  re-attached  as  before,  followed 
by  the  guard  tube.  The  current  of  oxygen  is  now 
admitted  at  about  the  same  rate  as  in  carbon  deter- 
minations, the  combustion  tube  heated  and  kept  hot 
until  all  the  steel  is  burnt,  when  it  is  allowed  to  cool, 
the  current  of  oxygen  being  replaced  by  air  as  soon  as 
the  combustion  is  complete.  After  passing  for  a  further 
half-hour  the  weighing  tube  is  removed  and  re- weighed. 
The  increase  represents  the  weight  of  water  formed, 
which  divided  by  nine  represents  hydrogen.  A  blank 
estimation  should  be  carried  out  to  ensure  the  freedom  of 
the  oxygen  and  air  from  hydrogen,  but  the  blank  should 
not  yield  more  than  half  a  milligram  increase  in  weight. 


MANGANESE 

METHODS  for  the  estimation  of  manganese  are  very 
numerous,  and  the  results  obtained  by  most  of  them 
are  so  reliable  that  the  task  of  selecting  the  "  best  " 
method  is  very  difficult.  For  plain  steels  the  volu- 
metric methods  using  sodium  bismuthate  or  ammonium 
persulphate  are  widely  used  and  reliable,  and  the  former 
method  may  even  be  used  for  spiegeleisen  or  ferro- 
manganese,  if  suitable  precautions  are  taken,  though 
the  gravimetric  estimation  after  separation  of  the  iron 
as  basic  acetate  is  to  be  preferred.  The  estimation 
with  sodium  bismuthate  is  interfered  with  by  vanadium, 
and  to  a  less  extent  by  chromium,  but  approximate 
results  may  be  obtained  by  its  use  even  in  the  presence 
of  considerable  amounts  of  these  metals.  Where  the 
greatest  accuracy  is  desired  when  these  elements  are 
present,  they  must  first  be  removed,  one  of  the  simplest 
methods  being  that  depending  on  the  treatment  of  the 
nearly  neutral  solution  with  cadmium  carbonate,  barium 
carbonate,  or  zinc  oxide,  when  chromium  and  vanadium 
are  precipitated  and  manganese  remains  in  solution. 
If  the  steel  can  be  dissolved  in  nitric  acid  the  manganese 
may  be  separated  as  an  oxide  approximating  to  Mn02 
by  the  addition  of  small  amounts  of  potassium  chlorate 
and  boiling.  This  precipitate  always  contains  small 
quantities  of  foreign  matter,  and  should  be  dissolved  in 

42 


MANGANESE  43 

1-2  nitric  acid  containing  a  little  sulphurous  acid,  and 
the  manganese  estimated  by  the  bismuthate  method. 

Gravimetric  Estimation.  This  estimation,  than 
which  none  goes  more  smoothly  when  skilfully  carried 
out,  probably  needs  more  manipulative  ability  and 
experience  than  any  other.  Dissolve  5  grm.  of  steel 
in  30  c.c.  of  hydrochloric  acid  and  30  c.c.  of  water, 
and  when  all  is  dissolved  oxidize  the  iron  by  adding 
5  c.c.  strong  nitric  acid.  Dilute  the  solution  to  about 
250  c.c.  with  hot  water,  and  cautiously  add  ammonia 
until  the  colour  deepens  considerably,  and  then 
ammonium  carbonate  until  the  colour  of  the  solution 
changes  to  a  deep  red,  showing  that  the  free  acid  has 
been  neutralized  and  that  the  solution  contains  basic 
ferric  chloride.  Now  add  the  reagent  in  small  quanti- 
ties until  a  permanent  precipitate  is  just  produced, 
clear  this  up  with  the  least  possible  amount  of  hydro- 
chloric acid  and  heat  to  boiling.  Now  add  10  c.c.  of 
ammonium  acetate  solution  (33  per  cent,  acetic  acid 
neutralized  with  strong  ammonia),  just  boil,  and  make 
up  to  500  c.c.  at  the  boiling  temperature  in  a  graduated 
flask.  Allow  the  precipitate  to  settle,  and  filter  through 
a  large  dry  fluted  filter  paper  into  a  dry  flask.  Take 
250  c.c.  in  a  graduated  flask  at  the  boiling-point  and 
cool  under  the  tap  until  quite  cold.  Transfer  to  a 
litre  flask  and  add  2  or  3  c.c.  of  bromine,  shake  up, 
add  a  moderate  excess  of  ammonia,  heat  to  boiling, 
and  maintain  near  boiling-point  for  a  few  minutes. 
The  manganese  is  precipitated  in  black  flocks  which 
are  readily  filtered  off.  Wash  the  precipitate  with 
hot  water,  collecting  the  washings  in  another  beaker 
apart  from  the  main  filtrate,  as  sometimes  the  pre- 


44  MODERN    STEEL   ANALYSIS 

cipitate  has  a  tendency  to  run  through.  If  this  happens 
the  turbid  washings  should  be  re-filtered  through 
pulp  or  a  very  fine  filter  paper,  and  the  residue  finally 
added  to  the  main  precipitate.  Both  are  now  ignited 
in  a  hot  muffle,  and  the  residue  weighed  as  Mn304, 
containing  72-05  per  cent.  Mn.  Allowing  5  c.c.  for  the 
volume  of  precipitate  in  half  the  solution,  the  per- 
centage of  manganese  is  found  from  the  relation 
-7205  x  W 


M 

Mn= 


255       K 
500X5 


The  chief  difficulties  in  the  method  are  the  complete 
separation  of  the  iron  and  the  manipulation  of  rather 
large  precipitates  and  volumes  of  solution.  The 
efficiency  of  the  iron  separation  depends  on  the  exacti- 
tude of  the  neutralization  before  adding  the  acetate  ; 
ammonia  should  be  added  until  the  solution  is  so 
deeply  coloured  that  it  is  only  possible  to  see  through 
it  with  difficulty.  The  final  precipitate  should  always 
be  tested  for  impurities,  of  which  ferric  oxide  and  nickel 
are  the  most  likely,  although  alumina  and  oxides  of 
copper,  nickel,  and  chromium  may  also  be  present. 
There  is  no  need  to  fear  the  inclusion  of  manganese  in 
the  iron  precipitate  ;  one  precipitation  effects  a  com- 
plete separation  when  properly  carried  out. 

Estimation  with  Sodium  Bismuthate.  1*1  grm.  of  the 
steel  are  weighed  into  a  200  c.c.  conical  flask  and  treated 
with  30  c.c.  of  1-2  nitric  acid  and  heated.  When  the 
brown  fumes  are  all  driven  off,  sodium  bismuthate  is 
added  in  small  quantities  until  a  pink  colour  or  a  pre- 
cipitate of  manganese  dioxide  persists  after  five  minutes' 
boiling.  The  flask  is  then  removed,  the  solution  cleared 


MANGANESE  45 

up  by  adding  a  few  drops  of  sulphurous  acid  solution, 
and  finally  made  quite  cold  under  the  tap.  A  small 
excess  of  sodium  bismuthate  is  now  added,  the  flask 
shaken  and  allowed  to  stand  for  a  minute  or  so,  and 
the  contents  filtered  through  a  thick  pad  of  ignited 
asbestos.  This  step  presents  the  most  opportunity  for 
error,  as  it  is  difficult  to  see  whether  the  darkly  coloured 
solution  is  really  clear  after  filtering,  and  any  bismuthate 
which  passes  through  will  seriously  affect  the  result. 
The  filter  is  washed  with  2  per  cent,  nitric  acid  until 
the  washings  are  colourless.  A  measured  slight  excess 
of  roughly  decinormal  ferrous  sulphate  is  now  added, 
and  the  excess  at  once  titrated  back  with  decinormal 
permanganate.  The  total  amount  of  permanganate 
equivalent  to  the  ferrous  sulphate  added,  less  that 
employed  in  the  back  titration,  represents  the  amount 

N 
equivalent  to  the  manganese  in  the  steel.    1  c.c.  of  y^ 

permanganate  =  '00110  grm.  Mn  or  O'l  per  cent,  on 
1*1  grm. 

Estimation  with  Ammonium  Persulphate.  Weigh 
into  a  6  in.  by  1  in.  boiling  tube  0-25  grm.  of  the  sample, 
add  10  c.c.  1-2  nitric  acid,  heat  to  boiling,  and  boil  till 
all  brown  fumes  are  gone.  Cool  under  the  tap  and  add 
about  10  c.c.  of  silver  nitrate  solution  (1  grm.  per 
1000  c.c.).  Now  add  about  1  grm.  of  pure  ammonium 
persulphate  and  heat  to  boiling.  The  manganese  is 
oxidized  to  permanganate,  and  the  excess  of  per- 
sulphate begins  to  decompose  with  a  copious  evolution 
of  oxygen.  Cool  quickly  under  the  tap  before  all  the 
persulphate  is  decomposed,  otherwise  the  manganese 
may  be  precipitated  as  hydrated  oxide.  Transfer  the 


46  MODERN    STEEL   ANALYSIS 

liquid  to  a  small  conical  flask  and  titrate  with  sodium 
arsenite  solution  (6-94  grm.  As203  and  35  grm.  an- 
hydrous sodium  carbonate  per  2  litres).  The  titration 
is  carried  on  until  the  colour  changes  to  a  pale  green, 
but  different  workers  use  slightly  different  end  points, 
for  which  reason  the  arsenite  solution  should  be 
standardized  against  a  steel  of  known,  roughly  equal, 
manganese  content.  The  percentage  of  manganese  is 
then  readily  calculated  from  the  relation  of  the  amount  of 
arsenite  added  to  the  amount  required  by  the  standard. 
Mechanicalized  Method.  Messrs.  Ridsdale's  modi- 
fication of  the  persulphate  method*  is  arranged  to 
permit  of  adding  the  silver  nitrate  and  persulphate  each 
in  tablet  form — a  considerable  advantage  in  the  case  of 
persulphate.  It  is  exceedingly  simple  and  reliable  and 
consists  in  the  following  steps  : 

Weigh  0*2  grm.  of  sample  (0*1   grm.  if  Mn  is  over 

0*40  per  cent.). 

Place  in  test-tube  and  add  10  c.c.  nitric  acid  (1*10). 
Place  in  vessel  of  boiling  water,  as  in  colour  carbon 

determination,  till  dissolved. 
Add  one  No.  SA  tablet,  and  when  dissolved 
Add  one  No.  SB  tablet. 

Boil  exactly  one  minute  from  first  appearance  of  a  pink. 
Cool  and  titrate  with  arsenite  or  compare  colour  with 

standard. 

If  manganese  appears  very  high,  10  c.c.  of  water  and 
another  No.  SA  and  No.  SB  tablet  may  be  added  after 
the  first. 

*  Journal  of  the  Iron  and  Steel  Institute,  1911,  i,  332 ;  and 
elsewhere. 


MANGANESE  47 

Chromium.  Chromium  steels,  even  when  vanadium 
is  also  present,  yield  approximate  results  by  the 
bismuthate  method  as  described  above,  but  owing  to 
the  slow  oxidation  of  chromium  to  chromic  acid,  results 
are  always  a  little  high  and  the  error  increases  with  the 
time  during  which  the  solution  remains  in  contact 
with  the  bismuthate.  A  certain  amount  of  difficulty 
is  often  experienced  in  dissolving  chromium  steels.  If 
the  steel  will  not  dissolve  in  30  c.c.  1*2  nitric  acid  com- 
pletely, the  addition  of  20  c.c.  more  hot  water  may  be 
tried.  If  this  is  ineffective,  the  steel  may  yet  dissolve 
if  a  fresh  quantity  is  treated  with  20  c.c.  of  water  and 
30  c.c.  of  1*2  nitric  acid.  If  the  steel  still  will  not 
dissolve,  the  addition  of  10  c.c.  of  1:3  sulphuric  acid 
may  help  matters ;  but  if  even  this  fails,  a  fresh  quantity 
must  be  weighed  out  and  opened  out  by  prolonged 
gentle  heating  with  about  10  c.c.  of  1 : 3  sulphuric  acid. 
Solution  will  be  very  much  retarded  if  crystals  of  ferrous 
sulphate  are  allowed  to  separate.  Hydrochloric  acid 
must  not  be  employed,  as  it  decomposes  the  bismuthate. 

In  whatever  way  the  steel  is  got  into  solution,  at  least 
30  c.c.  of  1*2  nitric  acid  must  be  present  and  the  volume 
not  much  over  40  c.c.  The  bismuthate  estimation  is 
then  carried  out  as  usual. 

For  the  greatest  accuracy  the  manganese  and 
chromium  should  be  separated.  The  basic  acetate 
separation  is  not  interfered  with  by  chromium,  but 
it  is  quicker  to  employ  the  chlorate  method.  For 
this  separation  both  hydrochloric  and  sulphuric  acids 
must  be  absent,  and  if  the  steel  cannot  be  dissolved  by 
nitric  acid  alone  the  sample  should  be  dissolved  in 
6  c.c.  of  strong  nitric  acid  together  with  4  c.c.  of  hydro- 


48  MODERN   STEEL   ANALYSIS 

chloric  acid  in  a  400  c.c.  beaker,  and  after  evaporating 
just  to  dryness  evaporated  twice  more  with  nitric  acid 
to  remove  the  hydrochloric  acid.  The  residue  is  then 
taken  up  with  20  c.c.  strong  nitric  acid,  or  if  the  sample 
was  originally  dissolved  in  nitric  acid  alone  the  solution 
is  evaporated  to  low  bulk  and  20  c.c.  strong  nitric  acid 
added.  About  4  grm.  of  potassium  chlorate  are  now 
added  in  small  quantities  to  the  boiling  solution.  The 
manganese  separates  out  as  peroxide.  The  solution  is 
thoroughly  boiled  after  adding  the  last  of  the  potassium 
chlorate,  filtered,  after  cooling,  through  ignited  asbestos, 
and  the  precipitate  washed  three  times  with  strong 
nitric  acid.  If  the  nitric  acid  contains  nitrous  acid 
this  must  be  eliminated  by  boiling,  or  prolonged 
aspiration  of  air,  otherwise  loss  of  manganese  through 
reduction  will  occur.  The  precipitate,  which  may 
contain  a  number  of  impurities  in  small  amounts,  is 
now  dissolved  from  the  filter  by  passing  through  in 
small  quantities  30  c.c.  of  1-2  nitric  acid  containing  a 
little  sulphurous  acid.  The  solution  is  now  boiled  and  the 
estimation  finished  as  in  plain  steel,  except  that  there 
is  no  need  to  add  bismuthate  to  the  boiling  solution. 

Vanadium.  In  the  bismuthate  estimation  when 
ferrous  sulphate  is  added  to  reduce  the  permanganate, 
the  vanadium,  which  is  present  as  vanadate,  is  also 
reduced  to  the  blue  hypovanadate,  and  this  is  only 
slowly  re-oxidized  by  permanganate  in  the  cold,  which 
makes  the  exact  end  point  a  little  doubtful,  and  the 
solution,  of  course,  must  not  be  heated  or  the  nitric 
acid  present  will  react  with  the  ferrous  sulphate.  The 
estimation,  however,  is  quite  practicable,  and  is  to  be 
recommended  on  account  of  its  simplicity  if  not  much 


MANGANESE  49 

vanadium  is  present.  The  gravimetric  method  is  also 
applicable,  but  if  vanadium  is  high  some  difficulty  may 
be  experienced  in  getting  the  neutralization  point 
before  precipitating  the  iron,  as  a  brown  precipitate 
containing  both  iron  and  vanadium  is  formed  This 
should  not  be  re-dissolved,  but  the  estimation  pro- 
ceeded with,  taking  care  to 'add  only  a  small  excess  of 
acetate.  If  chromium  is  also  present,  or  if  the  vanadium 
content  is  high,  it  is  desirable  to  separate  manganese  as 
follows  :  The  sample  (2-2  grm.)  is  brought  into  solution 
in  nitric  acid,  or  nitric  acid  containing  a  small  quantity 
of  sulphuric  acid,  in  one  of  the  ways  mentioned  under 
Chromium  (supra).  The  solution  is  nearly  neutralized 
with  sodium  carbonate  and  transferred  to  a  50  c.c. 
graduated  flask.  A  sufficient  quantity  of  fairly  thick 
cream  of  cadmium  carbonate  or  zinc  oxide  with  water  is 
added  to  neutralize  the  remaining  acid  and  leave  a  slight 
excess  after  precipitating  the  chromium  and  vanadium. 
The  solution  is  diluted  to  the  mark  with  water,  shaken 
up,  and  allowed  to  settle.  After  filtering  through  a 
dry  filter  into  a  dry  flask,  25  c.c.  of  the  filtrate  are 
extracted  with  a  pipette  previously  rinsed  out  with 
the  solution,  and  transferred  to  a  200  c.c.  conical  flask. 
Strong  nitric  acid  (17  c.c.)  is  added,  the  solution  cooled, 
and  the  estimation  proceeded  with  by  adding  sodium 
bismuthate,  filtering,  and  titrating  as  in  steel.  1  c.c.  of 

Q-KMn04  =  O'l  per  cent.  Mn  if  2-2  grm.  was  originally 

taken. 

Titanium.  With  small  amounts  of  titanium  any  of 
the  methods  for  plain  steel  may  be  used.  With  ferro- 
titanium  some  difficulty  of  solution  in  nitric  acid  may 

4 


50  MODERN   STEEL   ANALYSIS 

be  experienced,  but  the  addition  of  a  few  drops  of 
hydrofluoric  acid  produces  perfect  solution,  and  the 
estimation  is  then  carried  out  as  in  steel,  with  sodium 
bismuthate.  The  amount  of  hydrofluoric  acid  added 
should  be  only  just  enough  to  effect  solution,  as 
otherwise  the  bismuthate  oxidation  will  be  interfered 
with. 

Tungsten.  Tungsten  does  not  interfere  with  the 
bismuthate  method  of  estimation  in  steel,  but  with 
high  manganese  content  a  separation,  preferably  by 
the  chlorate  process,  must  be  made.  If  hydrofluoric 
acid  has  been  used  in  effecting  solution  of  the  alloy, 
results  by  the  bismuthate  method  may  be  irregular. 
In  this  case  it  is  best  to  remove  hydrofluoric  acid  by 
evaporation  with  sulphuric  acid,  but  not  more  than 
3  per  cent,  by  volume  of  sulphuric  acid  must  be  present 
in  the  solution  oxidized  by  bismuthate. 

Spiegel  and  Ferro-Manganese.  Manganese  may 
be  rapidly  and  satisfactorily  estimated  in  these  alloys  by 
the  bismuthate  process,  if  precaution  is  taken  to  have 
plenty  of  nitric  acid  present  and  too  large  a  weight  of 
the  sample  is  not  taken.  The  commonest  cause  of 
failure  in  the  estimation  is  the  decomposition  of  the 
permanganate  after  formation  into  a  brown  iridescent 
scum,  consisting  essentially  of  peroxide  of  manganese, 
which  is  filtered  off  with  the  excess  of  bismuthate. 
This  trouble  can  be  avoided  if  the  following  details  are 
used.  Dissolve  0*22  grm.  of  spiegel  in  50  c.c.  1-2  nitric 
acid,  destroy  organic  matter,  and  reduce  any  peroxide 
formed  with  bismuthate  as  in  steel.  Cool,  add  bis- 
muthate, filter  through  asbestos  into  a  flask  containing 
50  c.c.  of  water,  and  finish  in  the  ordinary  way.  1  c.c. 


MANGANESE  51 

N 
^r  KMn04  =  0-5  per  cent.  Mn.    With  ferro-manganese 

the  weight  taken  should  be  about  one-fourth  that  of 
spiegel.  This  is  best  arranged  for  by  weighing  0-22  grm. 
which  is  dissolved  in  50  c.c.  1*2  nitric  acid,  and  the 
organic  matter  oxidized  in  the  usual  manner.  After 
reducing  any  oxidized  manganese  compounds,  the 
solution  is  diluted  to  100  c.c.  with  1*2  nitric  acid.  To 
25  c.c.  of  this  solution  25  c.c.  of  1-2  nitric  acid  are  now 
added,  followed  by  bismuthate,  and  the  estimation 

N* 
finished  as  usual,  1  c.c.  y^  KMn04  =  2-0  per  cent.  Mn 

under  the  above  conditions.  It  is  better  to  operate  as 
above  by  taking  an  aliquot  part  than  to  commence 
with  a  very  small  initial  weight,  chiefly  because  trouble 
from  want  of  homogeneity  in  the  sample  is  lessened, 
and  also  because  an  error  of  weighing  of  ^  milligram 
would  not  be  negligible  in  this  case. 

The  volumetric  method,  although  quicker,  is  less 
accurate  than  the  gravimetric  estimation,  and  the 
latter  is  to  be  recommended  when  speed  is  not  a  prime 
object.  The  details  are  precisely  the  same  as  for 
manganese  in  steel  (above),  except  that  1  grm.  only  of 
the  alloy  should  be  taken,  and  that  a  little  more  difficulty 
in  getting  the  neutralization  perfect  may  be  experienced 
on  account  of  the  large  amount  of  manganese  and  little 
iron  present. 


MOLYBDENUM 

MOLYBDENUM  is  frequently  present  in  high-speed 
steels,  its  effect  being  similar  to  that  of  tungsten,  with 
which  it  may  easily  be  confused  in  analysis.  Molyb- 
denum may  be  readily  separated  from  iron  by  the 
well-known  method  using  aqueous  caustic  soda,  and 
estimated  in  the  filtrate  as  lead  molybdate.  If  tungsten 
is  present  it  will  be  co -precipitated  as  lead  tungstate, 
and  molybdenum  and  tungsten  should  be  separated  by 
Ibbotson  and  Brearley's  method. 

Estimation  in  the  Absence  of  Tungsten.  Dissolve 
the  sample  (2  grm.)  in  20  c.c.  of  hydrochloric  acid  with 
the  aid  of  heat  and  oxidize  the  iron  by  adding  a  slight 
excess  of  nitric  acid.  Heat  to  boiling,  dilute  to  about 
100  c.c.  with  hot  water,  and  neutralize  nearly  all  the 
free  acid  with  caustic  soda,  but  leaving  the  solution 
clear  yellow  in  colour.  In  another  flask  heat  40  c.c. 
of  20  per  cent,  caustic  soda  to  near  boiling  and  pour 
the  contents  of  the  other  flask  carefully  into  the  middle 
of  the  solution  with  thorough  shaking.  Cool  and  make 
up  to  200  c.c.  in  a  graduated  flask,  and  filter  off  100  c.c. 
through  a  dry  filter.  Acidify  the  filtrate  with  hydro- 
chloric acid,  adding  about  5  c,c.  excess.  Heat,  add 
20  c.c.  of  4  per  cent,  lead  acetate  and  50  c.c.  of  ammonium 
acetate.  Heat  to  boiling  and  keep  hot  for  about  a 
quarter  of  an  hour  until  the  precipitate  settles  well. 

52 


MOLYBDENUM  53 

Filter  off,  wash  with  hot  water,  and  ignite  in  a  weighed 
porcelain  crucible  to  lead  molybdate  PbMo04  con- 
taining 26-16  per  cent,  of  molybdenum. 

Estimation  in  the  Presence  of  Tungsten.  The  fol- 
lowing method  is  due  to  Ibbotson  and  Brearley,  and 
gives  excellent  results.  Five  grams  are  dissolved  with 
gentle  heating  in  90  c.c.  of  hydrochloric  acid  plus  10  c.c. 
of  nitric  acid.  The  solution  is  evaporated  just  to 
dryness,  but  the  residue  must  not  be  baked.  The 
mass  is  taken  up  in  dilute  hydrochloric  acid  (20  per 
cent.)  and  the  tungstic  oxide  and  silica  filtered  off 
together,  all  the  molybdenum  remaining  in  solution. 
The  tungsten  and  silica  may  be  washed,  ignited,  weighed, 
and  separated  by  hydrofluoric  acid  if  their  estimation 
is  required.  The  filtrate  containing  the  molybdenum 
is  nearly  neutralized  with  caustic  soda  and  the  estima- 
tion proceeded  with  as  above  in  the  absence  of  tungsten. 


NICKEL 

NICKEL  seldom  occurs  in  steel  in  appreciable  quantities 
unless  specially  added.  High-speed  steels,  armour 
plate,  gun  steels,  and  other  steels  where  great  toughness 
is  required  often  contain  nickel.  High  nickel  alloys, 
such  as  Invar,  are  commercially  useful  in  view  of  the 
smallness  of  their  coefficient  of  expansion,  their  slight 
change  in  modulus  of  elasticity  at  moderate  tempera- 
tures, and  of  their  magnetic  properties. 

Qualitative  Detection.  There  is  no  very  simple  test 
for  the  detection  of  small  quantities  of  nickel  in  the 
presence  of  large  amounts  of  iron.  If  a  fair  amount 
(4  per  cent.)  is  present,  the  solution  of  the  steel  in 
dilute  sulphuric  acid  will  be  distinctly  greener  than 
that  of  a  plain  steel,  but  chromium  produces  the  same 
effect.  Amounts  down  to  0-1  per  cent,  may  be  detected 
if  chromium  is  absent  by  dissolving  1  grin,  of  the  sample 
and  1  grm.  of  a  similar  steel  containing  no  nickel  in 
about  10  c.c.  of  strong  hydrochloric  acid  and  comparing 
the  colours  of  the  solutions.  That  containing  nickel 
will  be  distinctly  greener.  If  there  is  any  tendency  to 
oxidation  a  little  stannous  chloride  solution  may  be 
added  without  interfering  with  the  test.  As  many 
varieties  of  steel  contain  traces  of  nickel,  its  absence 
from  the  standard  must  be  ascertained  with  certainty. 
Small  amounts  may  be  detected  by  pouring  the  nearly 

54 


NICKEL  55 

neutral  solution  in  nitric  acid  into  excess  of  ammonia, 
filtering  and  passing  H2S.  A  blue  solution  yielding  a 
black  precipitate  indicates  nickel,  but  copper  behaves 
similarly.  The  best  test  is  to  carry  through  an  estima- 
tion, which  takes  only  a  short  time. 

Volumetric  Estimation.  The  volumetric  estimation 
of  nickel  is  to  be  preferred  to  the  gravimetric  as  well 
for  its  accuracy  as  for  its  rapidity.  There  are  many 
variations  in  the  actual  details  of  the  various  procedures 
used,  but  most  depend  on  adding  excess  of  standard 
potassium  cyanide  solution  to  a  neutral  or  alkaline  solu- 
tion containing  the  nickel  and  titrating  the  excess,  after 
adding  a  little  potassium  iodide,  with  silver  nitrate 
until  the  appearance  of  a  yellow  turbidity  of  silver 
iodide  indicates  that  the  end  point  has  been  reached. 
Citric  acid  is  sometimes  used  to  keep  the  iron  in  solution 
when  ammonia  and  potassium  cyanide  are  added,  but 
this  results  in  the  production  of  a  very  dark  solution 
in  which  the  cloud  of  silver  iodide  is  only  seen  with 
difficulty,  while  if  chromium  is  also  present  the  diffi- 
culty is  much  increased  both  by  the  colour  and  the 
chemical  interference  of  chromium.  The  following 
method  is  but  little,  if  any,  longer  than  those  in  which 
citric  acid  is  employed,  and  as  the  final  titration  is 
made  in  a  clear  colourless  solution  the  end  point  is 
much  sharper. 

Dissolve  1  grm.  of  the  steel  in  a  600  c.c.  flask  in  a 
mixture  of  6  c.c.  nitric  acid  and  4  c.c.  hydrochloric 
acid.  Heat  gently  until  the  red  fumes  clear  and  only 
a  small  amount  of  clear  red  liquid  remains.  Add  about 
300  c.c.  of  hot  water,  and  then  dilute  ammonia  (1  : 10) 
until  the  free  acid  is  neutralized  and  the  solution  takes 


56  MODERN   STEEL   ANALYSIS 

on  a  deep  red  colour  which  can  only  be  seen  through 
with  difficulty,  but  contains  no  precipitate.  Cool 
completely  under  the  tap,  transfer  to  a  litre  graduated 
flask,  and  run  in  a  measured  quantity  of  standard 
potassium  cyanide,  more  than  equivalent  to  the  nickel 
present,  but  avoid  a  large  excess.  Add  20  c.c.  of 
ammonia  (1  :  1),  shake  up  and  dilute  to  the  mark. 
Pour  off  into  a  large  beaker,  cover  with  a  clock  glass, 
and  allow  to  stand  for  a  few  minutes  until  the  pre- 
cipitated ferric  hydroxide  has  subsided.  Pour  off 
exactly  500  c.c.  of  the  clear  liquid.  If  the  precipitate 
has  settled  well  it  is  quite  unnecessary  to  filter,  as  the 
small  amount  of  ferric  hydroxide  carried  forward  only 
interferes  with  the  subsequent  titration  in  so  far  as  it 
makes  the  liquid  turbid.  Add  to  the  500  c.c.  of  liquid, 
contained  in  a  large  conical  flask,  10  c.c.  of  1  per  cent, 
potassium  iodide  solution  and  run  in  standard  silver 
nitrate  (see  Appendix  I)  from  a  burette  until  a  drop 
just  produces  a  slight  opalescence  in  the  liquid  which 
does  not  disappear.  The  number  of  cubic  centimetres 
of  silver  nitrate  equivalent  to  the  total  amount  of 
potassium  cyanide  added,  less  twice  the  amount  used 
in  the  back  titration,  divided  by  ten,  represents  the 
percentage  of  nickel  in  the  steel.  The  potassium 
cyanide  used  should  be  titrated  against  the  silver 
nitrate,  using  the  same  conditions  of  dilution  and 
content  of  potassium  iodide  and  ammonia.  It  may 
also  be  standardized  against  a  pure  nickel  solution, 
but  the  result  obtained  is  identical  with  that  obtained 
with  silver. 

Dimethylglyoxime  (or  Acetyldioxime)    Method. 
This  method  is  particularly  to  be  recommended  in  the 


NICKEL  57 

presence  of  cobalt,  or  when  small  amounts  of  nickel 
are  to  be  estimated. 

Five  grams  of  the  sample  are  dissolved  in  hydrochloric 
acid  and  the  iron  separated  as  basic  acetate  exactly  as 
in  the  gravimetric  estimation  of  manganese.  The 
warm  filtered  solution — which  will  contain  a  trace  of 
acetic  acid — is  transferred  to  a  beaker  and  about  twice 
as  much  dimethylglyoxime,  1  per  cent,  alcoholic  solution, 
is  added  as  is  necessary  to  combine  with  the  nickel  (about 
eight  times  the  weight  of  nickel  present).  The  solution 
is  thoroughly  agitated  and  the  bright  red  precipitate 
allowed  to  settle.  The  precipitate  is  filtered  off  and 
washed.  It  may  then  be  either  weighed  in  a  Gooch 
crucible,  after  drying  at  100°,  as  the  nickel  salt  of 
dimethylglyoxime,  NiC8H1404N4,  containing  40-74  per 
cent.  Ni,  or  ignited  to  nickel  oxide.  If  the  latter  course 
is  adopted  the  precipitate  should  be  ignited  gently  at 
the  mouth  of  muffle  before  raising  to  a  bright  red  heat. 
Nickel  oxide  contains  78-7  per  cent.  Ni. 

Cobalt.  Cobalt  seriously  interferes  with  estimation 
of  nickel  cyanometrically,  as  it  combines  with  potassium 
cyanide  in  the  same  way  as  nickel — four  atoms  of  nickel 
being  about  equivalent  to  three  of  cobalt.  The  dimethyl- 
glyoxime method  is  not  invalidated  by  cobalt,  and 
should  be  used  if  this  element  is  also  present. 

Chromium.  Chromium  does  not  interfere  with  either 
of  the  above  methods,  but  produces  serious  complica- 
tions in  those  modifications  of  the  cyanometric  method 
in  which  the  iron  is  retained  in  solution  by  means  of 
citric  acid. 


NITROGEN 

NITROGEN  occurs  in  very  small  amounts  in  all  varieties 
of  steel.  Its  effect  on  the  properties  of  the  metal  is 
very  doubtful,  but  is  probably  slight,  although  some 
metallurgists  maintain  that  it  is  even  more  injurious 
than  phosphorus. 

No  satisfactory  method  for  the  estimation  of  nitrogen 
has  been  evolved.  The  work  which  has  so  far  been 
carried  out  tends  to  show  that  great  difficulty  will  be 
experienced  in  rinding  a  method  of  procedure  which 
will  estimate  the  total  nitrogen  present.  The  methods 
so  far  proposed  consist  in  the  solution  of  the  steel  in 
acids,  or  in  solutions  of  copper  salts,  followed  by 
estimation  of  the  ammonia  formed  from  the  nitrogen 
present  in  the  steel ;  or  in  heating  the  steel  in  vacua . 
Investigation  has  shown  that  in  the  solution  methods 
part  of  the  nitrogen  escapes  as  gas,  part  is  converted 
into  ammonia,  and  part  remains  with  the  residue  ; 
while  after  heating  to  1100°  in  vacua,  ammonia  can 
still  be  detected  when  the  steel  is  cooled  and  dissolved 
in  acids.  In  view  of  these  facts  it  is  evident  that  no 
very  definite  meaning  can  be  given  to  the  value  obtained 
by  the  following  solution  method,  but  it  is  included  as 
serving  to  show  any  variations  in  amount  of  nitrogen, 
and  in  view  of  its  having  been  used  in  a  modified  form 
to  obtain  a  considerable  number  of  data  on  the  nitrogen 
content  of  steels. 

58 


NITROGEN 


59 


Estimation.  A  considerable  quantity  of  ammonia- 
free  water  is  first  prepared  by  distilling  ordinary  distilled 
water  to  which  about  10  c.c.  per  litre  of  concentrated 


FIG.  9. 

sulphuric  acid  has  been  added,  and  is  preserved  in  an 
accurately  stoppered  glass  bottle. 

The  sample  (1  grm.)  is  weighed  and  placed  in  a 
300  c.c.  round  flask  which  has  previously  been  well 
rinsed  out  with  ammonia-free  water.  Ammonia-free 
water  (10  c.c.)  is  added,  followed  by  1J  c.c.  strong 


6o  MODERN   STEEL   ANALYSIS 

sulphuric  acid,  or  7  c.c.  strong  hydrochloric  acid,  and 
the  contents  of  the  flask  are  gently  heated  until  every- 
thing is  dissolved  except  a  slight  carbonaceous  residue. 
The  liquid  is  now  transferred  to  the  small  flask,  B  in 
the  diagram,  which  is  closed  by  a  ground  joint  greased 
with  vaseline  and  carries  tubes  as  shown.    An  ordinary 
ground-neck  wash-bottle  is  readily  converted  into  a 
suitable  distilling  flask.    Pure  sodium  carbonate  (40  c.c. 
of  10  per  cent,  solution)  is  added,  the  flask  quickly 
closed  and  attached,  and  steam  passed  through  from 
the  large  boiling  flask,  A.    The  distillate,  which  will 
contain  all  the  ammonia,  is  collected  in  the  250  c.c. 
graduated  flask.    When  just  filled  to  the  mark  it  is 
removed  and  a  further  50  c.c.  is  collected  in  another 
vessel.    This  last  portion  should  be  free  from  ammonia, 
but  if  not  the  distillation  must  be  continued  until  no 
more  ammonia  comes  over.    If  the  additional  50  c.c. 
was  free  from  ammonia  the  contents  of  the  flask  are 
thoroughly  mixed  by  shaking  and  50  c.c.  are  placed  in 
a  Nessler  comparison  cylinder  which  has  previously 
been  washed  out  with  the  same  solution.    To  another 
Nessler  cylinder  is  added  10  c.c.  of  a  standard  nitrogen 
solution  (made  by  dissolving  0-381 8  grm.  pure  ammonium 
chloride  in  1  litre  of  ammonia-free  water  and  diluting 
100  c.c.  of  this  solution  to  1  litre  with  ammonia-free 
water).    The  cylinder  is  then  filled  to  the  mark  with 
ammonia-free  water  and  placed  beside  the  other  on  a 
white  tile.    Nessler 's  solution  (2  c.c.,  see  Appendix  I) 
is  now  added  to  each  cylinder  and  the  colours  produced 
compared.    If  they  are  unequal  in  depth  another  com- 
parison cylinder  must  be  prepared,  using  less  or  more 
of  the  standard  solution.    It  is  not  permissible  to  add 


NITROGEN  6 I 

more  of  the  standard  to  the  liquid  already  containing 
Nessler  solution,  as  the  colour  produced  in  this  way 
is  dissimilar  and  does  not  spread  evenly  through  the 
liquid.  When  the  colour  has  been  matched,  the 
amount  of  nitrogen  standard  added  is  noted,  and  the 
percentage  of  nitrogen  calculated.  When  carried  out 
as  above,  1  c.c.  of  standard  =  -005  per  cent.  N  in  the 
sample  ;  or  1  c.c.  of  standard  =  -00001  grm.  N. 

A  blank  determination  must  be  made,  as  almost  any 
nitrogenous  impurity  in  the  reagents  will  form  ammonia 
when  boiled  with  caustic  soda  and  ferrous  hydroxide. 
The  blank  is  carried  out  by  adding,  after  a  distillation 
has  been  completed,  the  same  amount  of  acid  and  alkali 
to  the  distilling  flask  as  was  used  in  the  original  estima- 
tion. 

The  apparatus  should  be  thoroughly  boiled  out  for 
about  three  hours  before  an  estimation  is  made,  and  for 
part  of  the  time  there  should  be  no  water  in  the  con- 
denser. This  is  absolutely  essential  as  the  apparatus, 
particularly  the  rubber  connections,  is  liable  to  contain 
small  amounts  of  ammonia,  or  other  substances,  which 
when  distilled  in  steam  yield  a  brown  or  yellow  colour 
with  Nessler's  solution. 


OXYGEN 

OXYGEN  occurs  to  a  greater  or  less  extent  in  all  varieties 
of  steel,  but  is  practically  absent  from  pig  and  cast 
iron.  Methods  for  the  estimation  of  oxygen  have  been 
put  forward  by  a  number  of  workers,  but  until  recently 
no  reliable  method — that  is  to  say,  no  method  giving 
results  to  which  a  definite  meaning  could  be  assigned 
— was  known,  and  in  consequence  statements  as  to 
the  effect  of  oxygen  on  the  properties  of  the  steel  must 
be  accepted  with  considerable  reserve.  The  balance  of 
opinion  favours  the  view  that  oxygen  is  distinctly 
harmful  in  its  effects,  producing  accelerated  rusting 
and  making  the  metal  red-short,  but  some  workers  have 
held  that  the  presence  of  oxygen  increases  the  ductility 
of  the  metal.  Until  further  data  are  available  it  is  im- 
possible to  make  any  definite  statement  with  certainty. 
For  a  discussion  of  the  forms  of  combination  in  which 
oxygen  is  present  in  steel,  reference  may  be  made  to 
the  author's  paper  on  the  "  Estimation  of  Oxygen  in 
Iron  and  Steel "  (Carnegie  Scholarship  Memoirs  of  the 
Iron  and  Steel  Institute,  vol.  v.,  1913,  p.  70),  where  a 
review  of  the  methods  of  previous  workers  on  the 
estimation  of  oxygen  is  also  given.  The  conclusion 
is  arrived  at  that  oxygen  may  be  present  as  carbon 
monoxide,  carbon  dioxide,  ferrous  oxide,  manganous 
oxide,  and  slag,  and  also  in  combination  with  any 

62 


OXYGEN 

to    the    steel, 


63 

as    titanium, 


special  addition  to  the  steel,  such 
aluminium,  &c.  Evidence  is  brought  forward  for  the 
solubility  in  steel  of  the  first  four  compounds  and  the 
probable  insolubility  of  the  remainder,  a  conclusion 
which  makes  it  likely  that  any  harmful  effects  due  to 
oxygen  will  be  produced  by  the  first  four.  The  method 
about  to  be  described  takes  account  only  of  oxygen 


M 


Fm.  10. 

combined  in  these  four  ways,  but  as  a  consequence  of 
this  fact  is  probably  of  greater  usefulness  than  a 
method  estimating  the  whole  irrespective  of  its  mode 
of  combination. 

Estimation.  The  estimation  is  performed  as  follows  : 
Hydrogen  free  from  oxygen  is  generated  in  a  Kipp's 
apparatus  *  (not  shown  in  diagram)  by  the  action  on  zinc 
of  dilute  sulphuric  acid  (1  :  6),  free  from  nitric  acid  and 
oxides  of  nitrogen,  and  containing  about  5  grm.  of 
crystallised  ferrous  sulphate  per  100  cubic  centimetres. 
The  gas  is  purified  by  bubbling  through  strong  sulphuric 
acid  in  the  washing  bottle,  A,  from  which  it  passes  to 
B,  containing  solid  caustic  potash,  followed  by  calcium 
chloride .  It  is  then  thoroughly  dried  by  passing  through 

*  The  complete  apparatus  is  supplied  by  Messrs.  C.  E. 
Miiller,  Onne  &  Co.,  of  148  Holborn. 


64  MODERN    STEEL   ANALYSIS 

the  phosphorus  pentoxide  in  C.  All  rubber  connec- 
tions are  rendered  perfectly  gas-tight  by  a  covering  of 
"  Chatterton's  compound "  or  sealing-wax.  E  is  a 
vitreous  silica  tube  closed  at  one  end,  18  in.  long  by 
1  in.  in  internal  diameter,  the  walls  being  3  mm.  thick  ; 
it  is  connected  by  a  gas-tight  rubber  joint  with  the  glass 
extension,  F.  This  is  of  the  same  diameter,  carries  a 
side  tube,  L,  and  is  closed  by  a  glass  cap,  H,  which  fits 
over  the  end.  The  side  tube  L  carries  two  stopcocks, 
D  and  M,  on  a  T-piece.  D  is  connected  with  the 
hydrogen  supply,  and  M  with  a  Fleuss  pump.  The 
silica  tube  is  held  horizontally  in  a  strong  clamp  in 
such  a  manner  that  an  electric  furnace  can  be  placed 
round  it  for  9  or  10  in.  of  its  length,  and  can  be  removed 
at  will  without  disturbing  any  part  of  the  apparatus. 
The  steel  to  be  analysed  is  placed  in  a  nickel  boat 
(previously  ignited  in  hydrogen)  and  pushed  up  near 
the  closed  end  of  the  tube.  The  water  resulting  from 
the  reduction  is  absorbed  by  a  small  glass  boat  con- 
taining phosphoric  oxide  inserted  into  the  open  end 
of  the  tube  near  the  glass  cap.  ^ 

To  carry  out  a  determination,  the  silica  tube  is  first 
completely  freed  from  moisture  by  carrying  out  a 
blank  heat  with  an  unweighed  boat  of  phosphoric  oxide 
in  the  cold  end.  When  cold  the  nickel  boat  is  taken 
out  and  weighed.  About  20  grm.  of  steel  are  then 
placed  in  the  boat  and  the  whole  is  re-weighed.  The 
steel  should  be  in  the  form  of  drillings  or  turnings,  and 
preferably  free  from  moisture— this  is  readily  ensured 
by  keeping  the  drillings  in  a  desiccator.  A  small  glass 
boat  containing  phosphoric  oxide  is  weighed  in  a  special 
weighing  bottle  provided  with  small  feet  to  prevent 


OXYGEN  65 

rolling  on  the  balance  pan.  The  drillings  are  now 
placed  in  the  silica  tube  near  the  closed  end  and  a 
small  unweighed  boat  containing  phosphoric  oxide 
placed  near  the  open  end.  The  cap  is  replaced  and  the 
tube  evacuated  and  allowed  to  remain  so  for  a  minute 
or  two,  during  which  time  any  moisture  and  air  con- 
densed on  the  drillings  are  completely  removed.  Hydro- 
gen is  now  admitted  up  to  atmospheric  pressure,  and 
the  weighed  boat  of  phosphoric  oxide  substituted  for 
the  other.  While  the  change  is  being  made,  the 
hydrogen  completely  escapes  from  the  tube  and  is 
replaced  by  the  same  volume  of  laboratory  air.  A 
small  correction  is  made  for  the  amount  of  water  vapour 
introduced  in  the  air,  but  this  never  amounts  to  more 
than  1  or  2  milligrammes.  The  tube  is  now  exhausted, 
filled  with  hydrogen,  and  re-exhausted.  In  order  to 
remove  the  last  traces  of  air,  this  washing  out  with 
hydrogen  may  be  performed  twice.  Finally,  hydrogen 
is  admitted  up  to  half  or  two-thirds  atmospheric  pressure, 
which  is  readily  effected  by  arranging  that  the  volume 
of  the  purifying  apparatus  between  tap  D  and  the  tap 
on  the  Kipp's  apparatus  is  from  one  to  two  times  that 
of  the  silica  tube  and  attachment.  Then  (the  purifying 
apparatus  being  filled  with  hydrogen  at  slightly  more 
than  atmospheric  pressure)  by  shutting  off  the  Kipp's 
apparatus  and  making  connection  with  the  vacuous 
tube,  the  latter  is  filled  with  hydrogen  at  the  right 
pressure.  The  object  of  this  diminished  pressure  is 
to  prevent  the  cap  being  blown  off  by  the  increased 
pressure  due  to  the  expansion  of  the  gas  on  heating. 
The  electric  furnace — previously  heated  to  1000° — is 
now  pushed  over  the  end  of  the  tube  until  9  or  10  in. 

5 


66  MODERN   STEEL   ANALYSIS 

are  surrounded,  and  allowed  to  remain  there  for  three- 
quarters  of  an  hour,  or  less  if  the  drillings  are  fine. 
At  the  end  of  this  time  the  furnace  is  removed  and  the 
tube  allowed  to  cool.  The  cooling  is  greatly  assisted  by 
an  air-blast,  but  this  is  not  essential.  When  cold  it  is 
filled  with  hydrogen  up  to  atmospheric  pressure,  tap 
D  closed,  the  cap  removed,  and  the  P205  boat  quickly 
replaced  in  the  weighing  bottle  and  weighed.  The  loss 
in  weight  of  the  steel  is  always  slightly  greater  than 
the  gain  of  the  P205  boat  by  reason  of  the  loss  of  sulphur 
and  carbon.  A  complete  estimation  may  be  carried 
out  in  less  than  an  hour,  and  during  most  of  the  time 
the  operator  is  free  to  do  other  work. 

In  order  to  determine  the  amount  of  moisture  intro- 
duced when  the  tube  is  opened  for  the  insertion  of  the 
weighed  boat  of  phosphorus  pentoxide,  a  blank  deter- 
mination must  be  made.  This  is  done  by  carrying 
through  a  determination  as  above  with  no  steel  in  the 
tube.  It  is  important  to  introduce  the  boat  as  quickly 
as  possible,  as  it  rapidly  increases  in  weight  when  left 
exposed  to  the  atmosphere.  The  time  occupied  in 
removing  the  cap,  inserting  the  boat,  and  replacing  the 
cap  should  not  exceed  six  seconds,  and  may  be  less. 

The  state  of  the  sample  has  an  important  bearing  on 
the  result.  The  most  satisfactory  form  of  sample  for 
analysis  is  turnings  of  0-2  millimetre  (y^-g-  in.)  thickness, 
or  less.  In  practice,  if  drillings  are  clean  it  is  sufficient 
to  sift  out  the  finest  part  through  a  30-mesh  sieve  and 
work  on  these,  but  in  every  case  the  drillings  or  turnings 
must  be  taken  with  every  precaution  to  ensure  absence 
of  scale,  rust,  and  oil ;  and,  of  course,  the  drillings  or 
turnings  must  not  be  taken  off  hot. 


PHOSPHORUS 

PHOSPHORUS  is  present  to  a  greater  or  less  extent  in  all 
varieties  of  steel  and  iron,  and  in  view  of  its  important 
effect  on  the  properties  of  the  metal  its  estimation  is 
almost  invariably  required.  Probably  more  processes 
for  its  estimation  have  been  worked  out  than  for  any 
other  element,  but  the  differences  chiefly  consist  in 
variations  of  the  means  by  which  a  final  precipitate  of 
ammonium  phospho-molybdate  is  obtained  and  of  the 
further  treatment  of  this  compound. 

The  methods  described  below  are  adapted  to  meet 
various  needs — rapidity,  accuracy,  or  convenience  when 
performing  a  large  number  of  operations.  A  single 
estimation  can  be  made  by  the  permanganate  oxidation 
method  in  twenty  minutes  or  even  less,  but  although 
the  second  method  requires  nearly  a  day  for  a  complete 
estimation  a  large  number  can  be  performed  in  about 
the  same  time  as  by  the  other.  The  slower  method  is 
more  reliable  than  the  other,  chiefly  in  view  of  the  more 
satisfactory  separation  of  arsenic,  which  may,  if  not 
removed,  under  certain  conditions  be  co-precipitated 
with  the  phosphorus  ;  and  also  because  very  small 
precipitates  of  phospho-molybdate  separate  more  quickly 
and  completely  when  this  method  is  employed. 

Quick  Method.  Dissolve  2  grm.  of  the  sample  in 
45  c.c.  1-2  nitric  acid  in  a  300  c.c.  conical  flask  and  boil 

67 


68  MODERN    STEEL   ANALYSIS 

until  brown  fumes  are  gone.  Now  add  potassium 
permanganate  solution  (3  per  cent.)  in  sufficient  quantity 
to  produce  a  pink  coloration  or  brown  precipitate  after 
five  minutes'  boiling.  Remove  from  the  plate,  cool 
somewhat,  add  just  enough  sulphurous  acid  solution 
to  clear  up  the  precipitate,  and  cool  thoroughly.  Add 
ammonia  (1:1)  with  gentle  swirling  of  the  liquid  until 
the  colour  begins  to  deepen  but  still  just  remains 
yellow.  Now  heat  to  boiling,  remove  from  the  plate, 
and  add  at  once  30  c.c.  of  molybdate  reagent  (see 
Appendix  I),  shake  the  flask  vigorously,  and  allow  the 
precipitate  to  settle.  Precipitation  is  complete  almost 
at  once.  Filter  through  all  cm.  filter  paper  in  a  ribbed 
funnel  and  wash  the  flask  and  paper  free  from  iron  salts 
with  nitric  acid  (20  c.c.  per  litre),  and  then  wash  both 
flask  and  filter  free  from  acid  with  2  per  cent,  potassium 
nitrate  solution.  Four  washes  with  each,  paying 
particular  attention  to  the  edges  of  the  paper,  should 
be  enough.  Test  the  washings  to  make  certain  all  acid 
has  gone,  and  then  transfer  the  filter  and  its  contents 
back  to  the  flask,  add  a  measured  excess  of  standard 
caustic  soda  (see  Appendix  I),  and  shake  round  until  all 
the  yellow  precipitate  is  dissolved.  Now  add  a  drop 
or  two  of  phenol  phthalein  and  titrate  back  with  standard 
sulphuric  acid  until  the  colour  becomes  very  faint. 
The  acid  equivalent  of  the  caustic  soda  added,  less  the 
acid  used  in  the  back  titration,  represents  the  amount 
of  acid  equivalent  to  the  precipitate,  and  hence  the 
amount  of  phosphorus  is  readily  calculated.  It  is 

N 
quite  safe  to  assume  that  1  c.c.  j^  sulphuric  acid  equals 

•001350  grin.  P,  but  for  additional  security  the  acid 


PHOSPHORUS  69 

should  be  standardized  against  a  steel  of  known  com- 
position. It  is  generally  believed  that  arsenio-  and 
silico-molybdates  tend  to  come  down  with  the  precipitate 
obtained  as  above,  but  the  author  has  been  unable  to 
detect  the  presence  of  either  in  any  precipitate  examined. 
For  percentages  of  phosphorus  under  0*02  the  pre- 
cipitate may  only  form  with  difficulty,  and  in  this  case 
the  method  described  below  is  preferable. 

Long  Method.  Dissolve  5  grm.  of  the  steel  in  35  c.c. 
nitric  acid  and  25  c.c.  hydrochloric  acid  in  an  800  c.c. 
beaker,  and  evaporate  to  dry  ness  and  bake.  Take  up 
in  40  c.c.  strong  hydrochloric  acid,  boiling  with  the 
cover  on  until  all  is  dissolved,  and  then  evaporate  just 
to  dryness  and  take  up  in  about  20  c.c.  hydrochloric  acid 
and  evaporate  to  low  bulk.  Dilute  with  about  50  c.c. 
hot  water  and  add  pure  zinc  foil  in  sufficient  quantity 
to  reduce  all  the  iron  to  the  ferrous  condition,  when 
the  colour  of  the  solution  becomes  pale  green.  During 
this  step  the  arsenic  is  reduced  to  the  arsenious  con- 
dition and  in  great  part  evolved  as  arsine,  AsH3. 
Evaporate  as  far  as  possible,  thus  driving  off  the 
remaining  arsenic  as  arsenious  chloride.  Cool,  add 
30  c.c.  of  water  and,  cautiously,  20  c.c.  of  nitric  acid. 
Boil  till  brown  fumes  are  all  evolved  and  transfer  to  a 
600  c.c.  conical  flask.  Add  ammonia  (1:1)  until  all 
the  iron  is  precipitated  and  the  brown  mass  smells 
strongly  of  ammonia,  then  just  re-dissolve  the  pre- 
cipitate with  strong  nitric  acid,  finally  adding  4  c.c. 
excess.  Heat  to  boiling  and  deliver  into  the  centre 
of  the  rotating  solution  from  a  pipette  15  c.c.  of  10  per 
cent,  ammonium  molybdate  with  constant  shaking. 
All  flocks  of  molybdic  acid,  if  formed  at  all,  should  be 


70  MODERN   STEEL   ANALYSIS 

immediately  re-dissolved.  The  precipitate,  after  shaking 
and  standing  until  the  upper  liquid  is  clear,  is  filtered 
off,  and  may  be  treated  as  in  the  preceding  method,  or 
in  either  of  the  following  ways  :  (a)  Filter  on  a  smooth 
filter  paper  and  wash  the  precipitate  in  the  usual  manner, 
but  direct  the  washings  in  such  a  way  that  the  pre- 
cipitate is  all  carried  down  into  the  point  of  the  filter. 
Dry  the  filter  at  about  120°  in  an  air  oven.  When  dry, 
open  out  the  filter,  brush  the  precipitate  into  the 
balance-scoop,  and  weigh.  If  properly  performed  a 
negligible  amount  of  precipitate  will  remain  attached 
to  the  paper.  The  weight  of  precipitate,  multiplied  by 
0-0165,  equals  the  weight  of  phosphorus  in  the  steel 
taken.  (6)  The  precipitate  may  be  transformed  into 
the  equivalent  amount  of  lead  molybdate  and  weighed 
as  such.  This  is  the  most  satisfactory  way  of  dealing 
with  the  precipitate  for  accuracy,  as  the  precipitate  of 
lead  molybdate  settles  and  filters  very  readily,  may 
be  ignited  without  any  unusual  precautions,  and  weighs 
nearly  150  times  as  much  as  the  phosphorus  from 
which  it  results.  The  flask  and  filter  containing  the 
precipitate  are  washed  free  from  iron  with  dilute  nitric 
acid,  and  the  precipitate  is  then  dissolved  off  the  filter 
with  a  small  quantity  of  ammonia  and  returned  to  the 
flask,  the  filter  being  well  washed.  Strong  hydrochloric 
acid  (10  c.c.)  is  now  added,  the  solution  heated,  and 
then  10  c.c.  of  lead  acetate  (4  per  cent.)  added.  In 
another  flask  50  c.c.  of  20  per  cent,  ammonium  chloride 
and  50  c.c.  of  ammonium  acetate  are  heated  to  boiling 
and  then  the  contents  of  the  other  flask  are  added.  A 
white,  rather  flocculent  precipitate  of  lead  molybdate 
forms,  which  settles  readily  if  the  liquid  is  kept  hot 


PHOSPHORUS  71 

for  a  short  time.  This  is  filtered  off,  washed  with  hot 
water,  and  ignited  in  porcelain  in  the  muffle  without 
drying.  The  weight,  multiplied  by  0-007,  represents 
the  weight  of  phosphorus  in  the  amount  of  sample 
taken. 

Mechanicalized  Methods.  These  methods,  recently 
introduced  by  Messrs.  C.  H.  and  N.  D.  Ridsdale,*  con- 
stitute the  simplest  and  most  rapid  methods  at  present 
available.  The  addition  of  the  reagents  in  the  form 
of  tablets  of  pure  and  carefully  tested  materials,  and 
the  standardization  of  all  conditions,  lead  to  a  uniformity 
in  results  only  to  be  obtained  with  difficulty  by  other 
methods  ;  while  the  elimination  of  the  personal  element 
makes  possible  the  utilization  of  comparatively  unskilled 
labour. 

1.  Without  Separation  of  Arsenic.  The  sample  is 
dissolved  in  a  measured  volume  of  nitric  acid  (1*22,  of 
which  25  c.c.  neutralize  9*13  grm.  pure  anhydrous 
Na2C03),  simmered  gently,  and  oxidized  with  a  tablet 
containing  permanganate.  Another  tablet,  containing 
ammonium  chloride,  ammonium  nitrate,  and  ferrous 
sulphate  is  then  added,  the  liquid  simmered  till  clear, 
and  10  to  15  c.c.  of  10  per  cent,  ammonium  molybdate 
added.  The  liquid  is  next  shaken  for  one  minute,  allowed 
to  stand  for  two  minutes,  the  precipitate  filtered  off, 
washed,  and  titrated.  The  operations  are,  therefore, 
briefly  : 

Weigh  2  grm.  of  sample. 

Dissolve  in  31'5  c.c.  1*22  nitric  acid. 

Simmer  for  two  minutes. 

*  Journal  of  the  Iron  and  Steel  Institute,  1913,  i,  332 ;  and 
elsewhere. 


72  MODERN   STEEL   ANALYSIS 

Add  one  No.  4  tablet. 

Simmer  for  two  minutes. 

Add  one  No.  6  tablet  and  simmer  till  clear. 

Bring  to  a  volume  of  50  c.c.  in  a  marked  beaker. 

Boil,  and  add  10  to  15  c.c.  molybdate  solution  (10 
per  cent.). 

Shake  one  minute,  stand  two  minutes.  In  these 
circumstances  silicon  from  0*3  to  0*4  per  cent,  does 
not  interfere. 

2.  Arsenic  Separated.*  A  crude  precipitate  containing 
all  the  phosphorus  is  first  obtained  exactly  as  described 
above.  This  is  then  dissolved  in  alkali,  quickly  acidified 
with  hydrochloric  acid,  and  the  arsenic  reduced  with 
zinc  and  precipitated  as  sulphide  by  adding  zinc  sul- 
phide. The  excess  of  sulphuretted  hydrogen  is  removed 
by  boiling,  re-oxidation  effected  with  potassium  chlorate, 
and  the  free  acid  neutralized  with  sodium  acetate.  The 
solution  is  then  suddenly  and  completely  re-acidified 
with  nitric  acid,  and  ammonium  molybdate  and  nitrate 
added  together,  when  the  pure  phospho- molybdate 
separates.  The  method  consequently  consists  in  the 
following  operations  : 

Weigh  4  grm.  of  sample. 

Dissolve  in  62  c.c.  of  1'22  nitric  acid. 

Oxidize  with  two  No.  4  tablets. 

Add  two  No.  6  tablets. 

Boil  and  add  25  to  30  c.c.  10  per  cent,  ammonium 
molybdate. 

Filter  and  wash  free  from  iron  with  cold  water. 

Re-dissolve  in  0*6  grm.  pure  sodium  hydrate. 

Add  13  c.c.  HC1  (M6). 

*  Journal  of  the  Iron  and  Steel  Institute,  1913,  i. 


PHOSPHORUS  73 

Reduce  with  one  No.  9  talbet. 

Precipitate  arsenic  as  sulphide  with  one  No.  10  tablet. 

Filter. 

Boil  off  H2S. 

Re-oxidize  with  one  No.  11  tablet. 

Neutralize  with  one  No.  12  tablet. 

Add  a  solution  of  one  No.  13  tablet  (50  c.c.). 

Re-acidify  with  7-0  c.c.  nitric  acid  (1*42). 

Shake,  filter,  and  titrate  as  before. 

The  foregoing  descriptions  are  only  to  be  regarded  as 
outlines.  The  fullest  details  of  working  are  issued  with 
the  reagents  as  issued  by  Messrs.  Ridsdale  and  their 
agents.* 

*  See  Note  on  the  Estimation  of  Phosphorus  in  Steels  con- 
taining Arsenic,  page  103. 


SILICON 

THE  determination  of  silicon  in  steel  is  one  of  the 
simplest  and  most  accurate  estimations.  In  high 
silicon  alloys,  on  the  other  hand,  considerable  diffi- 
culties have  to  be  overcome,  which  arise  chiefly  from 
the  remarkable  power  possessed  by  these  alloys  of 
resisting  attack  by  reagents.  The  assistance  of  hydro- 
fluoric acid  cannot,  of  course,  be  called  in  to  effect  solu- 
tion for  this  estimation,  and  in  many  cases  fusion  with 
alkaline  oxidizing  agents  has  to  be  resorted  to.  In  the 
presence  of  tungsten  also  some  difficulty  may  be 
experienced.  No  volumetric  method  for  the  estimation 
of  silicon  has  so  far  been  made  use  of,  the  estimation 
in  practically  every  case  depending  on  weighing  the 
silicon  as  silica.  When  steel  is  dissolved  in  hydro- 
chloric acid,  contrary  to  the  behaviour  of  aluminium 
and  some  other  metals,  no  silicon  is  lost  as  silicuretted 
hydrogen.  A  certain  amount  of  silicon  is  always 
dissolved  when  steel  is  dissolved  in  acids — 
indeed,  with  nitric  acid  of  density  1*2  the  whole 
goes  into  solution — necessitating  evaporation  to  dry- 
ness  and  baking,  or  else  evaporation  with  sulphuric 
acid  till  white  fumes  are  given  off,  for  its  complete 
elimination. 

Estimation,    This  is  conveniently    carried    out    in 
conjunction  with  the  estimation  of  sulphur  (q.v.),  but 

74 


SILICON  75 

if  silicon  only  is  required  the  following  method  is 
quicker  :  5  grm.  of  the  steel  are  dissolved  in  40  c.c. 
of  strong  hydrochloric  acid  in  a  capacious  beaker 
covered  with  a  clock-glass.  When  all  is  dissolved  the 
cover  is  removed  and  the  whole  evaporated  gently  to 
dryness  and  gently  baked — not  on  the  hottest  part  of 
the  plate — until  the  mass  is  pinkish  brown.  The 
beaker  is  removed  and  cooled,  about  40  c.c.  of  strong 
hydrochloric  acid  added,  followed  by  about  200  c.c.  of 
hot  water  when  all  is  in  solution.  The  solution  is 
then  filtered  and  the  whole  of  the  precipitate  carefully 
transferred  to  the  filter  with  the  help  of  a  rubbered 
rod.  The  filter  paper  is  washed,  particularly  at  the 
edges,  alternately  with  hot  water  and  dilute  hydro- 
chloric acid,  until  completely  free  from  iron.  It  is  then 
ignited,  and  the  precipitate  brushed  out  and  weighed. 
Where  there  is  any  reason  to  fear  contamination  the 
ignited  precipitate  may  be  treated  with  hydrofluoric 
acid  followed  by  sulphuric  acid  and  ignited  again,  the 
loss  in  weight  representing  Si02  containing  46' 93  per 
cent.  Si,  or  the  precipitate  may  be  fused  with  potassium 
bisulphate,  as  described  later. 

High  Silicon  Alloys.  Ferro-silicon.  Samples  of 
ferro-silicon  vary  a  good  deal  in  the  ease  with  which 
they  can  be  attacked  by  reagents.  If  very  finely 
ground,  most  samples  are  completely  decomposed  by 
aqua  regia  and  may  be  examined  by  the  following 
method. 

Half  a  gram  of  the  exceedingly  finely  powdered 
alloy  is  weighed  into  a  400  c.c.  beaker  and  digested  for 
as  long  as  may  be  necessary  with  10  c.c.  of  nitric  acid 
and  30  c.c.  of  hydrochloric  acid.  When  no  black  specks 


76  MODERN   STEEL   ANALYSIS 

can  be  detected  in  the  residue  the  cover  is  removed  and 
the  bulk  of  the  acids  expelled  by  evaporation ;  but  the 
solution  must  not  go  to  dryness  or  the  silica  will  be 
contaminated  with  iron  compounds  which  are  almost 
impossible  to  remove.  Dilute  with  about  100  c.c.  of 
hot  water  and  filter.  Wash  the  precipitate  alternately 
with  dilute  hydrochloric  acid  and  water  twice,  evapo- 
rate filtrate  and  washings  to  dryness  and  bake  gently. 
Take  up  with  sufficient  concentrated  hydrochloric 
acid,  dilute,  and  filter  through  the  same  filter  paper. 
Wash  completely  free  from  iron,  dry  the  precipi- 
tate by  placing  the  filter  paper  point  downwards  in  the 
crucible  on  the  hot  plate,  then  ignite  very  strongly 
for  at  least  fifteen  minutes,  and  weigh.  If  skilfully 
carried  out  this  method  should  yield  a  perfectly  white 
precipitate. 

Other  Alloys.  Where  the  preceding  aqua  regia  process 
does  not  give  satisfactory  results  a  fusion  method  may 
be  resorted  to.  Fusion  of  the  finely  ground  alloy  with 
potassium  bisulphate  may  sometimes  be  used,  and 
this  method  has  the  advantage  in  speed;  but  sodium 
carbonate  intimately  mixed  with  from  10  to  20  per 
cent,  of  potassium  nitrate  is  effective  in  every  case. 
In  the  potassium  bisulphate  fusion  0.5  grm.  of  the  alloy 
is  cautiously  heated  with  2  grm.  of  bisulphate  in  a 
porcelain  crucible.  When  fumes  escape  the  crucible 
is  removed  from  the  mufEe  and  about  15  grm.  more 
bisulphate  are  added  in  two  lots,  the  whole  being 
finally  fused  for  at  least  a  quarter  of  an  hour  at  a  very 
low  red  heat.  The  crucible  is  then  removed,  cooled, 
and  boiled  out  with  20  per  cent,  sulphuric  acid,  and 


SILICON  77 

the  silica  filtered  off,  washed,  ignited,  and  weighed. 
A  careful  examination  for  unattacked  particles  should 
be  made.  If  fusion  with  alkalies  is  employed,  fuse 
0.5  grm.  with  10  grm.  of  the  fusion  mixture  for  about 
half  an  hour.  Cool,  dissolve  the  melt  in  water,  acidify 
with  sulphuric  acid  (1  :  3),  and  add  about  20  c.c.  of 
concentrated  acid  in  excess.  Evaporate  to  fumes, 
cool,  dilute,  filter  off,  and  weigh  the  silica. 

Tungsten  and  Molybdenum.  If  these  elements  are 
present  the  alloy  must  be  decomposed  with  aqua  regia. 
The  precipitate  is  invariably  contaminated  with  tungstic 
or  molybdic  oxide.  There  are  several  satisfactory  but 
troublesome  ways  of  separating  the  tungstic  oxide, 
of  which  may  be  mentioned  heating  to  just  below 
redness  in  a  stream  of  air  and  chloroform  vapour ;  and 
reducing  the  two  in  hydrogen  and  then  passing  a  current 
of  chlorine  at  a  low  red  heat.  In  both  these  methods 
the  tungsten  is  carried  away  as  volatile  chlorides  of 
varying  compositions,  while  the  silica  remains  and 
may  be  weighed.  Silica  and  tungstic  acid  cannot 
be  satisfactorily  separated  by  means  of  ammonia,  as 
silica  is  appreciably  dissolved  by  this  reagent.  The 
simplest  procedure  is  to  weigh  the  two  together,  in  a 
platinum  crucible,  and  then  to  remove  the  silica  by 
adding  hydrofluoric  acid,  followed  by  sulphuric  acid. 
After  driving  off  the  excess  of  acids  and  igniting  the 
residue,  tungstic  acid  is  weighed  and  silica  determined 
difference. 

Other  Elements.  The  ignited  precipitate  is  occasionally 
found  to  be  contaminated  with  other  elements  not 
generally  supposed  to  cause  trouble.  In  such  cases, 


78  MODERN   STEEL   ANALYSIS 

where  the  impurity  is  of  doubtful  composition,  but 
probably  consists  of  metallic  oxides  or  basic  salts, 
fusion  with  potassium  bisulphate  or  pyrosulphate  will 
usually  remove  the  contamination.  After  dissolving 
out  the  melt  with  water  the  silica  may  be  filtered  off 
and  weighed. 


SULPHUR 

SULPHUR,  which  is  one  of  the  most  injurious  elements 
occurring  in  steel,  is  present  in  larger  or  smaller  amounts 
in  all  varieties,  and  its  estimation  is  correspondingly 
important.  The  estimation  depends  on  its  conversion 
into  either  sulphuretted  hydrogen  or  barium  sulphate, 
the  former  process  being  generally  known  as  the 
evolution,  the  latter  as  the  gravimetric,  method.  In- 
numerable modifications  and  combinations  of  the  two 
processes  have  appeared  and  continue  to  appear, 
especially  in  the  German  journals.  The  explanation 
is  to  be  found  in  the  importance  of  the  estimation  and 
in  the  great  effect  which  certain  details,  not  usually 
considered  important  in  other  estimations,  produce  in 
the  results  obtained.  Without  attempting  to  sum- 
marize the  literature,  the  following  processes  may  be 
relied  on  to  give  good  results  if  due  attention  is  given 
to  the  points  emphasized. 

By  Evolution.  Five  grams  of  the  sample  in  the  form 
of  moderately  thin  drillings  or  turnings  are  weighed 
into  a  500  c.c.  round  flask  (Fig.  10).  The  drillings  must 
not  be  too  thick — about  0-5  mm.  (-gV  in.)  is  a  desirable 
thickness.  The  rubber  stopper,  carrying  a  thistle 
funnel  and  delivery  tube  as  shown,  is  placed  in  position 
and  50  c.c.  of  ammoniacal  cadmium  acetate  solution 
(see  Appendix  I)  placed  in  the  300  c.c.  beaker  and  diluted 

79 


80  MODERN   STEEL   ANALYSIS 

with  its  own  volume  of  water.  Hydrochloric  acid 
(50  c.c.)  is  diluted  with  50  c.c.  of  water  and  the  mixture 
raised  to  the  boiling-point.  The  hot  hydrochloric  acid 
is  now  poured  down  the  thistle  funnel  and  the  contents 


FIG.  10. 

of  the  flask  maintained  at  the  boiling-point,  but  not 
boiled  vigorously,  until  the  steel  is  completely  dissolved. 
During  the  solution  of  the  steel,  fumes  of  ammonium 
chloride  rise  above  the  surface  of  the  liquid  in  the 
beaker.  Experience  shows  that  the  absorption  by  this 
means  is  complete,  and  that  a  guard  absorption  tube 


SULPHUR  8 1 

is  unnecessary.  When  solution  is  complete  the  liquid  is 
boiled  for  a  minute  and  the  flame  removed.  The  most 
important  point  in  the  whole  procedure  is  to  make  the 
evolution  as  rapid  as  possible.  The  beaker  is  then 
removed  and  the  delivery  tube  washed  into  it.  The 
estimation  of  the  precipitated  cadmium  sulphide  may 
be  carried  out  in  various  ways,  but  the  following  is 
the  simplest  method  ensuring  accuracy.  The  solution 
is  filtered  through  a  11  cm.  filter  paper  and  washed 
once  with  dilute  ammonia  (10  per  cent.).  It  is  un- 
necessary to  wash  the  precipitate  completely  free  from 
the  mother  liquor.  The  filter  paper  and  precipitate  are 
then  placed  in  a  300  c.c.  conical  flask  and  shaken  up 
with  about  50  c.c.  of  water.  Sufficient  dilute  hydro- 
chloric acid  is  now  added  just  to  acidify  the  liquid,  and 
a  small  measured  excess  of  standard  iodine  solution 
run  in.  After  thoroughly  shaking  up  for  about  half  a 
minute  the  excess  of  iodine  is  titrated  back  with 
standard  thiosulphate,  using  starch  solution  as  indi- 
cator. Only  the  clear  starch  solution  should  be  added, 
and  if  the  solution  is  made  up  following  the  directions 
in  Appendix  I  no  difficulty  will  be  experienced  in 
getting  the  starch  solution  to  settle  clear.  From  the 
number  of  c.c.  of  iodine  consumed  by  the  precipitate 
the  percentage  of  sulphur  is  calculated  from  the  relation 
H2S  +  I,  =  2HI  +  S. 

N 
Whence     1  c.c.  r^  iodine  =  -001603  grm.  S, 

N  . 
or  1  c.c.  ~  iodine  =  -03207  per  cent.  S  on  5  grm. 

N 
If  to  100  c.c.  —  iodine  solution  are  added  60-3  c.c. 


82  MODERN   STEEL   ANALYSIS 

of  water  a  solution  is  obtained  containing  7*94  grm. 
iodine  per  litre  and  of  which  1  c.c.  =  -001  grm.  S. 

If  the  filtration  of  the  cadmium  sulphide  precipitate 
is  omitted  and  the  whole  solution  titrated  as  above 
after  just  acidifying  with  hydrochloric  acid,  practically 
the  same  figure  is  obtained  as  a  rule,  but  occasionally 
this  leads  to  high  results,  owing  to  the  liquid  containing 
some  product  of  the  evolution  capable  of  combining 
with  iodine,  other  than  sulphuretted  hydrogen. 

Gravimetric  Estimation.  The  gravimetric  estimation 
of  sulphur  in  steel,  although  appearing  on  the  surface 
perfectly  straightforward  and  simple,  is  the  estimation 
which  gives  most  trouble  to  the  inexperienced  chemist. 
In  view  of  the  frequency  with  which  the  estimation 
has  to  be  made  and  the  conclusions  based  on  the  results, 
the  details  of  the  procedure  are  given  here  with  the 
greatest  fullness,  with  the  reasons  for  their  inclusion. 

Five  grams  of  the  sample  are  dissolved  in  25  c.c.  of 
hydrochloric  acid  together  with  35  c.c.  of  nitric  acid 
in  an  800  c.c.  long  beaker.  The  solution  takes  place 
very  energetically,  and  unless  a  beaker  at  least  of  the 
size  mentioned  is  used,  covered  with  a  clock-glass, 
considerable  loss  is  likely  to  take  place.  When  the 
reaction  is  over  the  cover  is  removed,  drained  into  the 
beaker,  and  roughly  1  grm.  of  pure  potassium  nitrate 
added.  The  above  proportions  of  acid  are  so  adjusted 
that  on  evaporation  a  residue  of  ferric  nitrate,  not 
chloride,  is  left.  The  solution  is  now  gently  evapo- 
rated on  the  hot  plate  to  complete  dryness  and  baked 
on  the  hottest  part  of  the  plate  for  half  an  hour.  This 
baking  breaks  up  the  ferric  nitrate  into  ferric  oxide  and 
oxides  of  nitrogen,  and  at  the  same  time  oxidizes  away 


SULPHUE  83 

the  soluble  carbon  compounds  and  renders  the  silica 
insoluble.  The  potassium  nitrate  is  added  with  the 
object  of  preventing  loss  of  sulphur  by  the  breakdown 
of  ferric  sulphate  into  ferric  oxide  and  sulphur  trioxide, 
the  sulphuric  acid  being  assumed  to  combine  with  the 
potassium.  Whether  this  is  indeed  the  case  may  be 
considered  doubtful,  and  for  low  sulphur  steels  the 
author  has  not  observed  any  loss  from  the  omission  of 
this  detail ;  but  its  retention  is  desirable,  as  it  is  so  little 
trouble  to  include.  The  baked  mass  is  now  removed 
from  the  plate  and  allowed  to  cool.  The  cover  is 
replaced,  40  c.c.  strong  hydrochloric  acid  added,  and 
the  beaker  replaced  on  the  plate  and  maintained  just 
at  the  boiling-point  until  all  the  ferric  oxide  has  dis- 
solved from  the  bottom  and  sides  of  the  beaker.  The 
cover  is  then  removed  and  drained,  and  the  contents 
evaporated  gently  until  the  volume  is  reduced  to  such 
an  extent  that  a  skin  begins  to  form  on  the  surface  of 
the  liquid,  when  10  c.c.  of  5  per  cent,  hydrochloric  acid 
are  added  and  the  beaker  removed.  During  this  pro- 
cedure the  last  of  the  nitric  acid  is  removed  and  the 
large  excess  of  hydrochloric  acid  evaporated.  This  is 
necessary  as  barium  sulphate  does  not  precipitate  well 
from  strongly  acid  solutions,  while  nitrates  tend  to  be 
carried  down  with  the  precipitate.  The  solution  is 
now  diluted  to  about  50  c.c.  and  filtered  through  an 
11  cm.  ashless  filter  paper  into  a  200  c.c.  beaker.  The 
paper  is  washed  two  or  three  times  with  water  and 
once  with  1  per  cent,  hydrochloric  acid,  making  the 
filtrate  up  to  about  100  c.c.  The  washing  of  the 
precipitate  can  then,  if  desired,  be  continued  to  complete 
freedom  from  iron,  neglecting  the  washings,  and  the 


84  MODERN   STEEL   ANALYSIS 

silica  ignited  and  weighed.  The  filtrate  is  now  boiled 
with  the  cover  on  and,  when  boiling,  20  c.c.  of  10  per 
cent,  barium  chloride  are  run  in  in  a  succession  of 
drops  from  a  pipette  introduced  through  the  lip  of  the 
beaker.  The  boiling  should  not  be  stopped  by  the 
addition.  If  care  is  exercised  no  iron  salts  will  dry  on 
the  sides  of  the  beaker,  but  if  this  has  happened  they 
must  be  re-dissolved  after  adding  the  barium  chloride 
by  cautiously  treating  them  with  a  few  drops  of  strong 
hydrochloric  acid  from  a  pipette.  The  solution  is  now 
boiled  for  a  few  minutes  and  allowed  to  stand  for 
several  hours.  By  adding  the  barium  chloride  in  the 
way  described  above,  the  barium  sulphate  is  precipitated 
granular  and  in  a  condition  to  be  easily  filtered,  and 
precipitation  is  complete  in  three  or  four  hours,  though 
it  is  generally  convenient  to  let  the  solution  stand 
overnight.  The  barium  sulphate  is  filtered  either 
through  a  pulp  filter  or  a  close-grained  ashless  paper. 
Max  DreverhofFs  quantitative  barium  sulphate  filter 
papers  are  excellent.  It  is  then  washed  several  times 
with  water  and  not  more  than  twice  with  very  dilute 
(1-5  per  cent.)  hydrochloric  acid,  using  about  5  c.c. 
each  time  and  washing  with  water  in  between.  When 
completely  free  from  chloride  two  or  three  more  washings 
are  given  and  the  precipitate  and  paper  ignited  in  an 
open  dish  or  capacious  crucible  for  about  half  an  hour 
at  a  moderate  red  heat  in  a  muffle.  Under  these  con- 
ditions the  barium  sulphide  formed  by  reduction  of 
the  sulphate  by  the  filter  ash  will  be  re-oxidized  by  the 
air.  The  dish  is  then  cooled  in  a  desiccator  and  the 
contents  brushed  out  and  weighed.  Treatment  of  the 
drecipitate  with  nitric  aud  sulphuric  acids  does  not 


SULPHUR  85 

lead  to  an  increase  in  weight  of  more  than  1  milligram 
on  a  precipitate  weighing  2  centigrams. 

Determination  of  Blank.  As  the  reagents  employed 
in  this  estimation  invariably  contain  small  amounts  of 
sulphur,  a  blank  determination  is  necessary.  The 
conditions  of  the  estimation  must  be  copied  as  nearly 
as  possible,  and  this  is  most  conveniently  managed 
either  by  taking  in  one  case  double  the  quantity  of 
reagents  for  the  same  amount  of  steel,  when  the  differ- 
ence in  the  weights  of  barium  sulphate  found  represents 
the  blank  due  to  the  ordinary  amount  of  reagents  ; 
or  by  taking  in  one  case  double  the  amount  of  steel 
used  in  the  other  case,  when  the  difference  between 
twice  the  weight  of  the  barium  sulphate  from  the 
smaller  weight  of  steel  and  that  from  the  other  weight 
represents  the  blank.  The  determination  of  blank  by 
simply  evaporating  the  reagents  with  a  little  potassium 
nitrate,  taking  up  in  hydrochloric  acid  and  precipitating, 
is  unsatisfactory  and  will  lead  to  errors. 

Estimation  of  Sulphur  in  Special  Steels.  When 
the  elements  mentioned  below  are  present  a  modified 
procedure  is  necessary. 

Vanadium.  For  low  percentages  of  vanadium  either 
of  the  above  methods  may  be  used,  but  should  the 
vanadium  steel  be  difficult  of  solution  the  evolution 
method  will  give  low  results.  With  high  percentages 
of  vanadium,  if  silicon  is  low,  the  gravimetric  method 
may  still  be  employed,  but  with  silicious  ferro- 
vanadiums  a  fusion  method  must  be  employed.  One 
gram  of  the  alloy  powdered  as  finely  as  possible 
is  fused  with  20  grm.  of  pure  anhydrous  sodium  car- 
bonate and  about  5  grm.  of  potassium  nitrate  for  half 


86  MODERN   STEEL  ANALYSIS 

an  hour.  The  melt  is  dissolved  out  with  water  acidified 
with  hydrochloric  acid  and  evaporated  to  dry  ness. 
The  mass  is  taken  up  with  dilute  hydrochloric  acid, 
filtered,  again  evaporated  to  dryness,  and  taken  up 
again  with  as  little  dilute  hydrochloric  acid  as  possible. 
It  is  now  filtered  if  necessary,  diluted  to  about  100  c.c., 
and  precipitated  with  barium  chloride  as  above. 

Silicon.  High  silicon  steels  and  ferro-silicon  can 
usually  be  dissolved  by  aqua  regia,  but  after  evaporating 
to  low  bulk  the  solution  should  be  diluted  and  the 
bulk  of  the  silica  separated  before  evaporating  to 
complete  dryness  and  baking ;  otherwise  the  silica  will 
take  up  a  considerable  amount  of  other  matter.  With 
this  alteration  the  gravimetric  method  may  be  employed, 
but  in  view  of  the  difficulty  of  solution  the  evolution 
method  is  inapplicable. 

Titanium.  Titanium  steels  present  no  additional 
difficulties.  With  ferro-titanium  the  evolution  method 
may  generally  be  used,  but  a  fusion  method  is  most 
satisfactory.  Proceed  as  in  ferro-vanadium,  but  extract 
the  melt  with  water  only,  whereby  all  the  constituents 
except  aluminium,  phosphorus,  silicon,  vanadium, 
tungsten,  and  molybdenum  (if  present)  remain  in  the 
residue.  A  second  fusion  may  be  necessary.  The 
united  filtrates  are  then  acidified  with  hydrochloric 
acid,  evaporated  to  dryness,  taken  up  in  hydrochloric 
acid,  filtered,  diluted  to  about  100  c.c.,  and  precipitated 
with  barium  chloride. 

Tungsten  and  Molybdenum.  The  evolution  method 
is  not  applicable  as  tungsten  alloys  are  not  completely 
decomposed  in  all  cases,  while  both  elements  prevent 
the  complete  evolution  by  forming  an  insoluble  sulphide. 


SULPHUR  87 

The  gravimetric  method  is  usually  applicable  without 
alteration  in  the  presence  of  molybdenum,  but  tungstic 
acid  is  precipitated  in  varying  amounts  with  the  barium 
sulphate,  if  not  completely  eliminated  along  with  the 
silica.  The  precipitate  may  be  freed  from  these 
impurities  by  filtering  on  pulp  and  boiling  the  washed 
precipitate  and  pulp  with  30  per  cent,  ammonia,  after- 
wards re-collecting  the  precipitate  and  pulp  and  washing 
with  ammonia.  If  aqua  regia  will  not  completely 
dissolve  the  alloy  it  should  be  fused  with  four  or  five 
times  its  weight  of  potassium  nitrate,  cooled,  boiled 
out  with  water,  the  dish  removed.  Hydrochloric  acid 
is  added,  and  the  solution  evaporated  to  dry  ness, 
again  taken  up  with  hydrochloric  acid,  filtered,  and 
the  estimation  continued  as  in  steel;  but  the  same 
precautions  should  be  taken  as  before  to  avoid  con- 
tamination of  the  precipitate  with  tungstic  or  molybdic 
acid. 


TITANIUM 

TITANIUM  is  a  fairly  common  constituent  of  steel, 
especially  American  varieties,  but  the  amount  does 
not  often  exceed  1  per  cent.  Its  office  is  similar  to 
that  of  vanadium — to  eliminate  impurities  by  carrying 
them  into  the  slag — and  it  has  been  credited  with  a 
very  beneficial  effect  in  removing  nitrogen.  If  specially 
added  to  steel,  a  rich  ferro-titanium  alloy  is  made 
use  of,  which  may  contain  up  to  80  per  cent,  of 
titanium. 

In  steel,  the  most  convenient  mode  of  estimation  is 
to  make  use  of  the  colour  developed  with  hydrogen 
peroxide  by  titanic  compounds  dissolved  in  nitric  or 
sulphuric  acids,  but  a  gravimetric  method  depending 
on  the  precipitation  of  titanic  acid  and  ignition  of  this 
compound  to  oxide  may  be  used.  Ferro-titaniums 
vary  a  good  deal  in  their  behaviour — chiefly  in  the 
readiness  with  which  they  pass  into  solution — and 
the  titanium  content  is  most  conveniently  estimated 
volumetrically  together  with  the  iron,  and  the  latter 
estimated  separately  and  allowed  for. 

Colorimetric  Estimation.  This  method  is  only  appli- 
cable in  the  absence  of  vanadium.  Dissolve  1  grm. 
of  the  steel  under  examination  and  1  grm.  of  a  similar 
steel  containing  no  titanium  separately  in  20  c.c.  of 
1  : 3  sulphuric  acid,  boiling  thoroughly.  If  any  con- 

88 


TITANIUM  89 

siderable  amount  of  carbon  remains,  it  should  be 
filtered  off  and  examined  qualitatively  for  titanium, 
but  this  is  not  usually  necessary.  Cool,  and  dilute  to 
about  50  c.c.  in  comparison  cylinders.  Add  to  both 
10  c.c.  of  hydrogen  peroxide  solution  (see  Appendix  I), 
and  stand  for  a  few  minutes .  Match  the  colour  produced 
in  the  sample  by  adding  to  the  other  a  sufficient  amount 
of  the  standard  titanium  solution  (see  Appendix  I), 
and  hence  calculate  the  percentage.  The  estimation 
may  also  be  performed  on  the  same  sample  as  that  for 
manganese  by  the  bismuthate  method,  if  the  per- 
manganate colour  is  just  cleared  up,  by  adding  a  drop 
of  ferrous  sulphate,  and  this  saves  the  trouble  of  weighing 
another  sample. 

Care  should  be  taken  that  the  comparison  solution 
is  in  all  respects  similar  to  the  other,  especially  in 
respect  of  nickel,  copper,  molybdenum,  and  chromium 
content.  Molybdenum  and  chromium,  if  present  in 
fair  amount,  make  the  estimation  unreliable. 

Gravimetric  Method.  Dissolve  the  sample  (5  grm.) 
in  50  c.c.  1  :  3  sulphuric  acid  with  the  aid  of  heat.  If 
the  residue  is  very  small  the  estimation  may  be  con- 
tinued ;  but  if  it  is  considerable  it  should  be  filtered  off, 
ignited,  fused  with  sodium  carbonate,  and  the  mass 
returned  to  the  solution.  Evaporate  the  whole  until 
fumes  begin  to  appear.  Dilute  carefully  and  filter  off 
the  silica.  Add  a  small  excess  of  sulphur  dioxide,  heat 
to  near  boiling,  and  add  ammonia  until  a  small  per- 
manent precipitate  forms.  Clear  this  up  with  a  drop 
or  two  of  sulphuric  acid — avoiding  excess.  Add 
10  grm.  of  sodium  thiosulphate,  boil  thoroughly,  and 
allow  to  settle.  Filter,  and  wash  the  precipitate  with 


90  MODERN   STEEL  ANALYSIS 

very  dilute  warm  acetic  acid.  Ignite,  and  weigh  as  TiOa 
containing  60-0  per  cent.  Ti. 

If  the  estimation  is  carried  out  as  above,  the  pre- 
cipitate should  be  free  from  everything  but  traces  of 
iron,  aluminium,  and  phosphorus.  Iron  may  be  com- 
pletely eliminated  by  re-solution  in  sulphuric  acid  and 
re-precipitation;  but  aluminium  and  phosphorus,  if 
present  in  any  quantity,  must  be  eliminated  by  fusion 
with  sodium  carbonate  and  extraction  with  water. 

Ferro-Titanium.  Either  the  gravimetric  method  just 
described  may  be  used — working  on  0-5  grm.  instead 
of  5  grm. — or  the  following  volumetric  method.  Ferro- 
titaniums  generally  dissolve  pretty  readily  in  moderately 
dilute  acids,  but  in  some  cases  fusion  with  potassium 
bisulphate  may  be  resorted  to  with  advantage.  If 
potassium  bisulphate  is  used,  it  is  well  first  to  fuse  it 
alone,  and  to  add  the  weighed  sample  when  the  surface 
has  solidified.  Fifteen  minutes  fusion  at  not  too  high 
a  temperature  is  usually  ample — and  it  should  not  be 
possible  to  detect  any  gritty  particles  after  that  time 
on  stirring  with  a  platinum  wire.  The  crucible  and 
contents  are  then  cooled,  and  boiled  with  dilute  sulphuric 
acid.  If  the  gravimetric  method  is  employed  the  whole 
is  evaporated  to  fumes  to  separate  silica  and  the 
estimation  continued  as  above. 

With  some  varieties  of  ferro-titanium  containing  high 
silicon,  fusion  with  bisulphate  is  insufficient.  In  these 
cases  the  alloy  may  be  first  roasted  in  a  platinum  crucible, 
cooled,  treated  with  hydrofluoric  acid,  evaporated,  and 
then  fused  with  bisulphate ;  or  it  may  be  roasted,  fused 
with  sodium  carbonate  and  potassium  nitrate,  and 
dissolved  from  the  crucible  with  nitric  or  sulphuric  acid. 


TITANIUM  91 

Volumetric  Estimation.  Dissolve  1  grm.  of  the  alloy 
in  dilute  sulphuric  acid  (25  c.c.  1  : 3).  If  the  alloy 
does  not  dissolve  readily,  solution  must  be  effected  by 
one  of  the  methods  indicated  above.  If  any  consider- 
able residue  remains  after  the  action  of  the  acid  has 
stopped  it  must  be  filtered  off,  fused  with  sodium 
carbonate  and  a  little  sodium  peroxide,  dissolved  out 
in  sulphuric  acid,  evaporated  to  fumes,  diluted,  filtered 
from  silica,  and  the  filtrate  added  to  the  main  solution. 
The  solution  is  now  diluted  to  exactly  250  c.c.  in  a 
measuring  flask,  and  two  quantities  of  100  c.c.  each 
( =  04  grm.  sample)  withdrawn.  To  one  portion  is 
added  about  50  c.c.  of  sulphurous  acid  solution,  and 
the  liquid  is  then  boiled  vigorously  in  a  flask  covered 
with  a  watch-glass  until  all  sulphur  dioxide  has  been 
expelled.  The  solution  is  then  cooled  and  titrated 
with  standard  permanganate — the  titration  repre- 
senting the  iron  present.  While  these  operations  are 
being  carried  out  the  other  100  c.c.  portion  is  treated 
with  about  2  grm.  of  pure  zinc  foil  (free  from  iron)  in 
a  covered  flask  and  left  to  simmer  gently  on  the  hot 
plate,  a  little  more  acid  being  added  if  necessary. 
Small  amounts  of  titanium  (under  0*1  grm.)  are  quickly 
reduced,  but  for  safety  it  is  well  to  let  the  reduction 
occupy  at  least  fifteen  minutes.  When  all  the  zinc 
has  been  dissolved,  5  grm.  of  iron  alum,  dissolved  in 
25  c.c.  of  well-boiled  water,  is  added,  and  the  solution 
quickly  cooled  and  titrated  with  permanganate.  The 
difference  between  this  titration  and  the  preceding  one 
represents  the  amount  of  permanganate  reduced  by  the 

N 
titanium— 1  c.c.  -r^KMn04  =  -00481  grm.  Ti. 


TUNGSTEN 

TUNGSTEN  is  one  of  the  commonest  additions  to  modern 
steels.  It  confers  the  property  of  retaining  magneti- 
zation over  long  periods  and,  with  other  metals,  is  a 
constituent  of  most  of  the  self-hardening  and  high- 
speed steels  so  widely  used  at  the  present  day.  A 
fairly  large  selection  of  methods  for  its  estimation  is 
available,  most  of  which  terminate  with  the  weighing 
of  the  tungsten  as  tungstic  oxide,  though  lead  tungstate 
is  an  alternative  form.  Volumetric  methods  for  its 
estimation  have  not  so  far  been  employed,  though 
doubtless  a  method  could  be  readily  devised  depending 
on  the  solution  of  tungstic  acid  in  standard  alkali  and 
titration  of  the  excess. 

Rapid  Estimation.  The  following  method  is  rapid 
and  widely  used.  It  is  stated  to  yield  slightly  low 
results,  but  the  author  has  not  found  this  to  be  the 
case.  Dissolve  5  grm.  of  the  sample  as  far  as  possible 
in  80  c.c.  strong  hydrochloric  acid,  and  when  action 
slackens  add  cautiously  just  enough  strong  nitric  acid 
to  oxidize  the  iron  and  effect  solution.  Remove  the 
cover  and  evaporate  until  tungstic  oxide  begins  to 
separate,  add  80  c.c.  of  hot  water,  and  boil.  The 
precipitated  tungstic  acid  is  allowed  to  settle  in  a 
warm  place,  filtered  off,  and  washed  alternately  with 
hot  water  and  very  dilute  hydrochloric  acid.  The 

92 


TUNGSTEN  93 

precipitate  contains  generally  as  impurity  ferric  oxide, 
silica,  and  possibly  chromium  and  titanium  oxides  in 
traces.  If  the  amount  of  these  is  not  negligible,  the 
silica  should  be  removed  by  means  of  hydrofluoric  and 
sulphuric  acids.  The  tungstic  acid  is  then  extracted 
from  the  residue  by  warming  with  a  little  dilute 
ammonia,  the  insoluble  matter  filtered  off,  and  the 
filtrate  evaporated  to  dryness  in  a  platinum  dish  and 
ignited.  The  weight  of  W03  obtained,  multiplied  by 
0-7931,  represents  tungsten.  Another  equally  satis- 
factory method  is  to  fuse  the  precipitate  of  impure 
tungstic  oxide  with  potassium  bisulphate,  raising  the 
temperature  gradually  to  a  red  heat,  when  the  fusion 
should  be  clear  and  transparent.  The  fusion  is  boiled 
out  with  ammonium  carbonate  solution,  the  insoluble 
matter  collected,  ignited,  and  weighed.  This  weight 
when  subtracted  from  the  weight  of  the  original  pre- 
cipitate gives  the  weight  of  the  tungstic  oxide  present. 

The  above  method  may  be  used  for  the  estimation 
of  tungsten  in  all  high-speed  steels,  and  is  not  interfered 
with,  except  as  mentioned  above,  by  chromium,  molyb- 
denum, nickel,  cobalt,  or  vanadium. 


URANIUM 

URANIUM  is  a  somewhat  rare  addition  to  steel,  and 
when  present  is  always  the  result  of  an  intentional 
addition.  It  is  stated  to  confer  properties  on  the  metal 
similar  to  those  due  to  nickel,  i.e.  toughness  and  resist- 
ance to  shock,  but  to  a  more  marked  extent.  The 
following  method  is  largely  based  on  Brearley's  mono- 
graph "  The  Chemistry  of  Uranium,"  and  has  been 
found  to  work  well. 

Estimation.  Dissolve  10  grm.  of  steel  in  50  c.c.  strong 
hydrochloric  acid  diluted  with  50  c.c.  hot  water.  If  more 
than  -1  per  cent,  of  silicon  is  present  it  must  be  elimi- 
nated by  taking  to  dryness,  baking,  and  re-dissolving  in 
hydrochloric  acid  (40  c.c.).  Copper,  if  present,  is 
eliminated  by  diluting  to  about  300  c.c.  and  passing 
sulphuretted  hydrogen.  The  precipitated  copper 
sulphide  is  filtered  off  together  with  the  silica,  and  the 
solution  boiled  to  eliminate  sulphuretted  hydrogen. 
About  ten  times  as  much  microcosmic  salt  as  there  is 
uranium  present  is  now  added,  followed  by  ammonia 
till  a  faint  permanent  precipitate  is  produced.  This  is 
cleared  up  with  the  smallest  possible  excess  of  hydro- 
chloric acid,  and  10  grm.  of  sodium  thiosulphate  and 
15  c.c.  of  acetic  acid  are  added  and  the  solution  boiled 
for  about  fifteen  minutes.  It  is  then  allowed  to  settle 
and  the  precipitate  filtered  off.  The  mixed  phosphates 

94 


URANIUM  95 

of  aluminium,  iron,  and  uranium  are  then  dissolved 
in  a  little  nitric  acid  (1-2)  and  the  solution  rendered 
only  feebly  acid  by  ammonia.  It  is  then  heated  nearly 
to  boiling  and  poured  into  about  100  c.c.  warm  10  per 
cent,  ammonium  carbonate  solution,  which  is  vigorously 
stirred  the  while.  The  solution  is  now  preferably  set 
aside  in  a  warm  place  for  an  hour  or  two,  and  then 
filtered.  The  solution,  containing  the  uranium,  is 
brought  to  boiling,  microcosmic  salt  ten  times  the 
weight  of  the  uranium  added,  and  nitric  acid  till  just 
neutral.  Ten  grams  of  sodium  thiosulphate  and  15  c.c. 
acetic  acid  are  added,  and  the  solution  boiled  fifteen 
minutes  as  before.  The  precipitate  is  filtered  off, 
washed,  and  ignited.  The  green  residue,  which  is  rather 
hygroscopic,  is  weighed  and  contains  68' 55  per  cent, 
uranium.  As  this  figure  does  not  correspond  to  a 
simple  chemical  compound,  it  is  preferable  to  convert  it 
into  uranyl  pyrophosphate  (U02)<f2Q7  by  treating  with 
a  very  little  nitric  acid  and  igniting  at  low  redness. 
The  yellow  mass  of  uranyl  phosphate  obtained  contains 
66-81  per  cent.  U.  It  is  also  rather  hygroscopic,  and 
should  be  kept  in  a  good  desiccator  and  weighed  without 
delay. 


VANADIUM 

VANADIUM  is  seldom  or  never  added  to  steel  in  con- 
siderable quantity  with  the  intention  of  preparing  an 
alloy  steel  of  superior  qualities.  It  is  chiefly  used  as  a 
"  scavenger "  to  eliminate  impurities  by  combining 
with  them  and  carrying  them  into  the  slag.  As  a 
result  vanadium  steel  usually  contains  well  under 
1  per  cent,  of  vanadium;  but  ferro-vanadium  alloys, 
which  are  made  use  of  as  a  convenient  vehicle  for 
adding  the  vanadium,  may  contain  30  or  40  per  cent. 

The  detection  of  vanadium  offers  no  great  difficulties 
as  its  reactions  are  at  once  delicate  and  characteristic. 
Usually  it  is  sufficient  to  dissolve  about  -2  grm.  of  the 
sample  in  dilute  sulphuric  acid  (1  :  3),  adding  a  slight 
excess  of  nitric  acid  to  oxidize  the  iron  and  complete 
solution,  followed  by  a  few  drops  of  hydrogen  peroxide 
to  the  cold  diluted  liquid.  A  dark  brownish-red 
coloration  indicates  vanadium.  The  colour  is  almost  dis- 
charged by  adding  a  fair  excess  of  ferrous  sulphate. 
Titanium  under  the  same  conditions  yields  a  bright 
straw-yellow  solution,  but  the  vanadium  colour  is 
always  clearly  distinguishable  even  when  considerable 
amounts  of  titanium  are  present.  The  titanium  colour 
is  not  at  all  readily  discharged  by  a  considerable  excess 
of  ferrous  sulphate.  Another  very  characteristic  re- 
action is  the  rapid  formation  of  a  black  colour  on  heating 

96 


VANADIUM  97 

a  little  of  a  vanadium  solution  with  a  solution  of  aniline 
in  dilute  sulphuric  acid,  which  also  contains  a  little 
potassium  chlorate.  The  colour  is  at  first  purple,  then 
deep  plum,  and  finally  black,  and  is  due  to  the  pro- 
duction of  aniline  black,  resulting  from  the  accelerated 
oxidation  of  the  aniline  by  the  chlorate  in  presence 
of  vanadium  compounds.  The  most  sensitive  test  is 
Gregory's  (C.N.,  1909,  100,  221),  which  is  not  interfered 
with  by  titanium,  molybdenum,  or  tungsten,  even  if 
present  in  large  quantities,  but  iron  and  chromium  must 
be  separated.  The  solution,  containing  a  little  potassium 
chlorate,  is  taken  to  fumes  with  sulphuric  acid  until  all 
chlorine  is  evolved  and  cooled.  Twenty  cubic  centi- 
metres of  a  solution  of  strychnine  in  concentrated 
sulphuric  acid  (4  grm.  per  litre)  are  then  added.  An 
intense  colour  immediately  develops  if  vanadium  is 
present,  and  attains  its  maximum  intensity  in  about 
ten  minutes.  By  comparison  with  a  similarly  treated 
standard  a  colorimetric  estimation  may  be  made. 

Separation  from  Iron  and  other  Constituents  of  Steel. 
By  pouring  a  nearly  neutralized  solution  of  the  steel 
into  boiling  10  per  cent,  caustic  soda,  vanadium  is 
completely  separated  as  soluble  vanadate  from  iron, 
nickel,  manganese,  copper,  and  all  but  traces  of 
chromium;  but  molybdenum,  tungsten,  titanium,  and 
aluminium  remain  associated.  The  addition  of  ammonia 
containing  about  5  per  cent,  ammonium  phosphate 
(Am2HP04)  to  a  solution  of  the  steel  precipitates  iron, 
manganese,  aluminium,  and  chromium  and  leaves  the 
vanadium  in  solution  with  copper,  and  part  of  the 
nickel,  tungsten,  and  molybdenum.  After  dissolving 
the  steel  in  aqua  regia  and  evaporating  to  dryness  and 

7 


98  MODERN   STEEL  ANALYSIS 

fusing  the  mass  with  sodium  carbonate,  adding  about 
0*5  grm.  of  finely  powdered  charcoal  during  the  last  ten 
minutes  of  the  fusion,  and  then  cooling  and  extracting 
with  water,  vanadium  is  separated  from  chromium, 
and  passes  into  solution  with  the  tungsten,  molyb- 
denum, and  aluminium.  Vanadium  may  be  separated 
from  all  metals  except  molybdenum  by  proceeding  as 
in  the  ordinary  phosphorus  determination,  but  adding 
about  ten  times  its  weight  of  sodium  phosphate  before 
adding  the  molybdate.  The  vanadium  is  then  all  in- 
cluded in  the  phospho-vanadio-molybdate  precipitated. 
Estimation.  In  view  of  the  difficulty  of  effecting 
a  satisfactory  separation,  vanadium  is  not  conveniently 
estimated  gravimetrically  in  complex  steels.  Volu- 
metric methods,  many  and  various,  have  been  described, 
and  though  most  approximate  to  the  vanadium  content, 
few  accurate  methods  are  known.  Quinquevalent 
vanadium  is  reduced  to  the  quadrivalent  condition  in 
acid  solutions  by  sulphurous  acid,  ferrous  sulphate, 
oxalic  acid,  and  some  other  reagents,  and  is  re-oxidized 
by  permanganate  readily  at  60-70°  C.,  and  slowly  at 
lower  temperatures.  Bichromate  does  not  effect  re- 
oxidation,  but  quadrivalent  vanadium  reduces  to  some 
extent  the  ferric  salts  of  the  mineral  acids,  producing 
ferrous  iron ;  so  that  when  the  quinquevalent  com- 
pound is  reduced  by  an  excess  of  ferrous  sulphate, 
bichromate  cannot  be  used  to  estimate  the  excess  of 
ferrous  sulphate  added  unless  special  precautions  are 
taken.  If,  however,  sodium  phosphate  considerably 
more  than  equivalent  to  all  the  iron  present  be  added, 
this  reduction  may  be  avoided  and  bichromate  used. 
Without  going  into  an  exhaustive  criticism  of  published 


VANADIUM  99 

methods,    the    following    procedures    will    be    found 
reliable. 

Colorimetric  Estimation.  Dissolve  1  grm.  of  the 
sample  and  1  grm.  of  a  similar  steel  free  from  vanadium 
in  10  c.c.  of  1  :  3  sulphuric  acid.  To  each  add  cautiously 
2  c.c.  strong  nitric  acid,  heat  till  the  solutions  are  clear 
and  fumes  have  disappeared,  and  cool.  Transfer  to 
comparison  glasses,  and  to  each  add  10  c.c.  of  hydrogen 
peroxide  solution  made  by  dissolving  about  2  grm.  of 
sodium  peroxide  in  100  c.c.  sulphuric  acid  (1 : 10). 
Dilute  with  water  until  the  solutions  are  equal  in  volume, 
and  match  the  colour  produced  by  the  vanadium  steel 
by  adding  to  the  other  a  sufficient  quantity  of  a  standard 
solution  of  vanadium  containing^  0'1778  grm.  V206 
dissolved  in  10  c.c.  strong  sulphuric  acid  and  diluted  to 
1  litre  (1  c.c.  =  -0001  grm.  V). 

The  above  procedure  can  hardly  yield  results  accurate 
to  OO4  per  cent.,  but  the  following  method  is  much 
more  sensitive.  Dissolve  1  grm.  of  the  sample  in  45  c.c. 
nitric  acid  (1  : 2)  and  add  1  c.c.  10  per  cent,  sodium 
phosphate.  Boil  till  all  fumes  are  off.  Cool  somewhat 
and  add  carefully  14  c.c.  of  ammonia  (1  : 1),  boil  until 
all  ferric  hydrate  is  re-dissolved,  remove  from  the  plate, 
and  add  30  c.c.  of  nitro-molybdate  solution,  shaking 
well.  The  vanadium  is  all  co-precipitated  with  the 
phospho-molybdate.  Filter  off  on  a  small  smooth  filter 
and  wash  free  from  iron  with  2  per  cent,  nitric  acid, 
finally  washing  with  water.  Wash  the  precipitate  into 
a  400  c.c.  beaker,  add  a  small  pinch  of  potassium 
chlorate  and,  cautiously,  20  c.c.  of  strong  sulphuric 
acid,  and  evaporate  on  the  hot  plate  till  fumes  are 
freely  evolved.  Remove  and  cool.  Take  an  amount 


100  MODERN   STEEL   ANALYSIS 

of  the  standard  vanadium  solution  roughly  equivalent 
to  the  expected  amount  of  vanadium  present,  add  a 
little  potassium  chlorate  and,  cautiously,  20  c.c.  of 
sulphuric  acid,  take  to  fumes  and  cool  as  before.  When 
cold  add  to  each  20  c.c.  of  a  solution  of  4  grm.  of 
strychnine  in  1  litre  of  strong  sulphuric  acid.  Allow 
to  stand  ten  minutes  and  match  the  colours  by  diluting 
the  stronger  with  sulphuric  acid. 

Gravimetric  Estimation.  The  following  modification 
of  Blair's  method,  though  rather  long,  gives  good 
results  :  Dissolve  5  grm.  of  a  steel  or  pig-iron  and 
correspondingly  less  of  a  high  vanadium  alloy  in  50  c.c. 
of  1-2  nitric  acid.  Evaporate  to  dryness  and  bake 
until  nitrates  are  decomposed,  taking  care  that  the 
mass  does  not  splash  up  on  to  the  sides  of  the  beaker. 
The  mass  can  then  be  easily  removed  from  the  beaker 
with  a  negligible  loss.  Powder  in  an  agate  mortar 
and  fuse  with  25  grm.  of  sodium  carbonate  and  2  grm. 
of  sodium  peroxide  in  a  platinum  dish  for  half  an  hour 
at  a  bright  red  heat.  Boil  out  the  fused  mass  with 
water,  filter,  and  nearly  neutralize  with  nitric  acid 
(1-2).  Boil  off  the  carbon  dioxide,  filter  if  necessary, 
dilute  to  500  c.c.  and  just  acidify — a  yellow  colour 
showing  the  presence  of  vanadium.  Add  5  grm.  of 
mercurous  nitrate  dissolved  in  as  little  water  as  possible 
and  a  small  quantity  of  mercuric  oxide  suspended  in 
water  to  neutralize  the  free  acid.  Boil,  filter,  and 
wash  with  hot  water,  and  ignite  carefully  after  drying. 
If  chromium,  tungsten,  and  molybdenum  are  absent, 
the  residue  will  consist  of  vanadium  pentoxide,  and 
the  weight  of  vanadium  present  may  be  calculated 
by  multiplying  by  0-5655.  If  present,  the  precipitate 


VANADIUM  10 1 

must  be  again  fused  with  10  grm.  of  sodium  carbonate 
and  1  grm.  sodium  peroxide  as  before,  dissolved  in  a 
little  water  and  filtered  if  necessary.  Pure  ammonium 
chloride  is  then  added  to  saturation — about  3'5  grm. 
will  be  needed  for  each  10  c.c. — the  solution  is  well 
stirred  and  allowed  to  stand  for  some  time.  The 
vanadium  is  precipitated  as  ammonium  metavanadate, 
and  may  be  filtered  off,  washed  with  saturated 
ammonium  chloride  containing  ammonia,  ignited,  and 
weighed  as  pentoxide. 

Volumetric  Estimation.  The  volumetric  estimation 
of  vanadium  by  the  following  method  is  much  more 
rapid  than  the  gravimetric  and  quite  as  accurate  if 
performed  with  care.  Dissolve  0'5  grm.  of  ferro- 
vanadium,  or  2-5  grm.  of  a  vanadium  steel,  in  30  c.c. 
of  sulphuric  acid  (1  : 3),  adding  10  c.c.  of  nitric  acid 
as  the  reaction  slackens.  A  little  hydrofluoric  acid 
will  effect  solution  if  the  sample  is  refractory.  Evapo- 
rate until  fumes  are  freely  evolved.  Dilute  with  100  c.c. 
1  :  3  sulphuric  acid  and  then  with  water  to  400-500  c.c. 
Heat  to  about  60°  or  70°  and  add  dilute  permanganate 
solution  drop  by  drop  until  a  faint  pink  colour  persists. 
Discharge  this  colour  by  carefully  adding  the  exact 
amount  of  ferrous  sulphate  necessary.  Now  add  50  c.c. 
of  10  per  cent,  sodium  phosphate  solution  and  cool. 
Add  an  excess  of  standard  ferrous  sulphate  solution 
and  titrate  back  with  bichromate,  using  ferricyanide 
of  potassium  as  an  external  indicator.  The  amount  of 
ferrous  sulphate  added,  less  that  equivalent  to  the 
bichromate  used  in  the  back  titration,  represents  the 

N 
amount  oxidized  by  the  vanadium.     1  c.c.        ferrous 


102  MODERN   STEEL   ANALYSIS 

sulphate  =  '00510  grm.  V.  This  method  is  interfered 
with  by  chromium,  but  not  by  any  other  metal  com- 
monly occurring  in  steel.  The  effect  of  chromium  may 
be  avoided  by  performing  the  first  oxidation  with 
permanganate  in  the  cold  solution  instead  of  at  65°, 
but  care  must  be  taken  that  enough  permanganate  is 
added  to  produce  a  really  permanent  coloration. 


NOTE  ON  THE  ESTIMATION  OF 

PHOSPHORUS  IN  STEELS 

CONTAINING  ARSENIC 

IN  view  of  the  contradictory  statements  as  to  the 
co-precipitation  of  arsenic  with  ammonium  phospho- 
molybdate,  the  following  results  obtained  by  the 
methods  described  in  the  foregoing  pages  are  of  some 
interest. 

The  steel  employed  was  supplied  to  the  author  with 
the  following  analysis  : 

C  0-435 

Mn  0-835 

Si  0-10 

P  0-040 

As  Present  but  not  estimated. 

Phosphorus  was  first  estimated  by  the  quick  method 
(p.  68)  and  the  mechanicalized  method  without  separa- 
tion of  arsenic  (p.  72).  Three  estimations  by  each 
method  were  made — in  the  first  no  more  arsenic  was 
added,  but  in  the  second  and  third,  roughly,  0*05  and 
0-10  per  cent,  of  arsenic  respectively  was  weighed 
out  as  As208  and  added  to  the  drillings  before  dis- 
solving. 

103 


104  MODERN    STEEL    ANALYSIS 

The  results  are  shown  below. 

I  II          III 

PEE  CENT.   PERCENT.    PERCENT. 

Arsenic  added        .         .     Nil  0-05         0-10 

/-Quick  method  .  0-041  0-039  ,0-040 

P  founds  Mechanicalized 

I    method         .  0-065  0-103  rO-127 

Other  estimations  were  carried  out  by  the  mechani- 
calized  "arsenic  separated"  method  (p.  73)  and  the 
long  method  (p.  70),  and  these  gave  : 

PERCENT.    PERCENT. 

Mechanicalized,  arsenic  separated  .    0*039      0*038 
Long  method       ....     0-040 

It  is  evident  from  these  figures  that  arsenic  only 
affects  the  short  mechanicalized  method,  which  is 
designed  to  carry  down  the  whole  of  the  arsenic  with 
the  phosphorus,  and  is  on  that  account  useful  as  showing 
the  combined  As  +  P  figure,  and  admits  of  the  simple 
estimation  of  arsenic  by  difference.  It  is,  of  course, 
impossible  to  disprove  the  statement  that  in  some  steels 
the  arsenic  present  behaves  differently  from  added 
arsenic.  It  is  also  possible  that  in  certain  cases  higher 
silicon  or  other  impurities  may  vitiate  the  quick  method, 
although  no  difficulty  has  been  encountered  so  far  from 
these  causes. 


ATOMIC  WEIGHTS 


Aluminium 

Antimony 

Arsenic 

Barium 

Bismuth 

Boron  . 

Bromine 

Cadmium 

Calcium 

Carbon 

Cerium 

Chlorine 

Chromium 

Cobalt  . 

Copper 

Fluorine 

Glucinum 

Gold     . 

Hydrogen 

Iodine  . 

Iron     », 

Lead    . 

Lithium 

Magnesium 


0  =  16 

Al 

27-1 

Sb 

120-2 

As 

74-96 

Ba 

137-37 

Bi 

208-0 

B 

11-0 

Br 

79-92 

Cd 

112-40 

Ca 

40-07 

C 

12-00 

Ce 

140-25 

Cl 

35-46 

Or 

52-0 

Co 

58-97 

Cu 

63-57 

F 

19-0 

Gl 

9-1 

Au 

197-2 

H 

1-008 

I 

126-92 

Fe 

55-84 

Pb 

207-10 

Li 

6-94 

Mg 

24-32 

105 


io6 


MODERN   STEEL  ANALYSIS 


Manganese    . 

Mercury 

Molybdenum 

Nickel  . 

Nitrogen 

Oxygen 

Palladium 

Phosphorus   . 

Platinum 

Potassium 

Selenium 

Silicon 

Silver   . 

Sodium 

Strontium     . 

Sulphur 

Tantalum 

Tellurium 

Thorium 

Tin       . 

Titanium 

Tungsten 

Uranium 

Vanadium     . 

Zinc 

Zirconium 


Mn 

O=16 
54-93 

Hg 
Mo 

200-6 
96-0 

Ni 

58-68 

N 

14-01 

0 

16-00 

Pd 

106-7 

P 

31-04 

Pt 

195-2 

K 

39-10 

Se 

79-2 

Si 

28-3 

Ag 

Na 

107-88 
23-00 

Sr 

87-63 

S 

32-07 

Ta 

181-5 

Te 

127-5 

Th 

232-4 

Sn 

119-0 

Ti 

48-1 

W 

184-0 

U 

238-5 

V 

51-0 

Zn 

65-37 

Zr 

90-6 

APPENDICES 


APPENDIX  I 

SOLUTIONS 

Acetate  of  Ammonia  : 

Ammonia  (-880)  .         .  100  c.c. 

Glacial  acetic  acid       .         .         .        114  c.c. 
Water        ....         .        228  c.c. 

Mix  the  ammonia  with  the  water  and  add  the  acetic 
acid.    Solution  should  just  redden  blue  litmus. 

Acetate  of  Cadmium  for  estimation   of   sulphur    by 
evolution  method : 

Crystallized  cadmium  acetate       .          25  grm. 
Ammonia  (-880)  ...        100  c.c. 

Water  up  to       .         .         .         .       1000  c.c. 

Dissolve  the  cadmium  acetate  in  part  of  the  water,  add 
the  ammonia,  and  dilute  to  1000  c.c.    Filter  if  necessary. 

Bichromate  of  Potassium,  standard,  for  chromium  : 

Pure  crystallized  K2Cr207    .         .     2-830  grm. 
Dissolve  in  water  and  dilute  to     .       1000  c.c. 
lc.c.=  -001  grm.  Cr. 
«  003159  Fe. 


HO  MODERN   STEEL   ANALYSIS 

Bichromate  of  Potassium — (con*.). 
1  c.c.  =  -004513  Fe203. 

=  -5770c.c.~KMn04. 

=  -0006334  grm.  Mn  as  KMn04. 
=  -001583  grm.  Mn  as  Mn02. 
=  -007320  grm.  I. 


Carbonate  of  Sodium,  for  standardizing  acid  for  phos- 
phorus determination  : 

Pure  anhydrous  sodium  carbonate     3-915  grm. 
Water  up  to       ....       1000  c.c. 

The  standard  sulphuric  acid  should  be  almost  exactly 
equivalent.  The  number  of  cubic  centimetres  of  acid 
equal  to  1  c.c.  of  the  above  solution  =  -0001  grm.  P. 

Carbonate  of  Sodium,  decinormal : 

Pure  anhydrous  Na2C03       .         .      5-303  grm. 
Water  up  to       ....      1000  c.c. 


Chloride  of  Calcium,  for  arsenic  estimation. 

Anhydrous  calcium  chloride  .  .  400  gm. 
Hydrochloric  acid  .  .  .  400  c.c. 
Water  to 1000  c.c. 

Add  the  calcium  chloride  to  a  small  quantity  of  water 
then  add  the  acid  and  dilute  to  1000  c.c. 


APPENDIX    I  III 

Cyanide  of  Potassium  for  nickel  estimation  : 

Cyanide  of  potassium,  crystallized  10  grm. 
Stick  potash,  about  ...  10  grm. 
Water 2500  c.c. 

Dissolve  in  a  small  quantity  of  water  and  place  in  a 
Winchester,  adding  water  until  nearly  filled.  Shake 
well.  This  solution  is  roughly  equivalent  to  the  silver 
nitrate  solution  used  in  nickel  estimation. 


Copper  Standard : 

Re-crystallized  CuS045H20  .         .      39-30  grm. 
Water  up  to       .        V       .         .       1000  c.c. 
10c.c.=  0-lgm.  Cu. 


Hydrate  of  Sodium,  for  phosphorus  determination : 

Caustic  soda,  purified  by  alcohol  .  8  grm. 
Barium  hydrate,  crystallized  «•'  1  grm. 
Water  up  to  one  Winchester. 

Dissolve  separately  in  water,  mix  in  a  Winchester, 
add  water  till  nearly  filled,  shake,  and  allow  to  settle. 
1  c.c.  is  roughly  equal  to  1  c.c.  sulphuric  acid. 


Iodide  of  Potassium  for  indicator  in  cyanometric  nickel 
determination : 

Potassium  iodide         ...        4  grm. 
Water  up  to       ....     100  c.c. 


112  MODERN   STEEL   ANALYSIS 

Iodine,  for  volumetric  estimation  of  sulphur : 

Pure  re-sublimed  iodine       .         .       7-96  grm. 
Potassium  iodide         .         .         .      12-0    grm. 

Water  to 1000  c.c. 

Dissolve  the  potassium  iodide  in  a  little  water  and 
add  it  in  small  quantities  to  the  iodine,  pouring  the 
strong  solution  into  a  litre  flask  before  adding  more 
iodide  solution.  When  all  the  iodine  has  been  dissolved 
dilute  to  1  litre. 

lc.c.=  -001  grm.  S. 

=  '02  per  cent,  on  5  grm.  samples. 
=  '01  per  cent,  on  10  grm.  samples. 

Molybdate  Solution,  for  precipitating  phosphorus  by  the 
quick  method  : 

Pure  molybdenum  trioxide  .         *        150  grm. 

Ammonia  (-880)  .         *        .        105  c.c. 

Water        ....        «;     315  c.c. 
Mix  the  ammonia  and  water,  and  add  to  the  molybdic 
oxide.    Stir  till  nothing  further  goes  into  solution,  and 
filter.    Pour  the  filtered  liquid  with  constant  stirring 
into 

Nitric  acid  (1-2)          .  .      1875  c.c. 

Molybdate  Solution,  for  both  long  and  mechanicalized 
methods : 

Ammonium  molybdate        *         .        260  grm. 
Water  to  fill       .  1  Winchester  quart. 

Dissolve  the  ammonium  molybdate  in  warm  water 
and  mix  in  the  Winchester. 


APPENDIX    I  113 

Nitrate  of  Silver,  for  cyanometric  nickel  estimation : 

Pure  re-crystallized  silver  nitrate  .      5-792  grm. 

Water  to 1000  c.c. 

1  c.c.=  -001  grm.  Ni. 
=  -003833  Ag. 


Nitric  Acid,  sp.  gr.  1-2  : 

Concentrated  nitric  acid  (1-42)      .    2  volumes. 
Water  3  volumes. 


Nitric  Acid,  sp.  gr.  1-135  : 

Concentrated  nitric  acid  (1-42)      .    2  volumes. 
Water  5  volumes. 


Nessler's  Solution : 

Potassium  iodide 
Mercuric  chloride 
Stick  potash 


62-5  grm. 
103  grm. 
150  grm. 


Dissolve  the  potassium  iodide  in  about  250  c.c.  and 
the  mercuric  chloride  in  400  c.c.  of  water,  and  set  apart 
a  few  c.c.  of  each.  Add  the  mercuric  chloride  until  a  per- 
manent precipitate  is  just  produced,  clear  this  up  by 
adding  the  remainder  of  the  potassium  iodide,  then 
add  more  mercuric  chloride  very  carefully  until  a 
precipitate  is  just  produced  again.  Now  dissolve  the 
potash  in  150  c.c.  of  water,  add  it  to  the  solution  and 
dilute  to  1  litre. 

8 


114  MODERN    STEEL   ANALYSIS 

Nitrogen  Standard : 

Pure    re-crystallized    ammonium 

chloride  ....     0-1909  grm. 

Ammonia-free  water  up  to  .         .        1000  c.c. 

lc.c.=  -00005  grm.  N. 

Permanganate  of  Potassium,  decinormal : 

Pure  re-crystallized  permanganate 

of  potassium  .         .         .         .3-16  grm. 
Water  up  to       ....       1000  c.c. 

Add  the  water  in  small  quantities  to  the  perman- 
ganate in  a  flask.  Shake  round  and  pour  off  the  con- 
centrated solution  into  a  litre  flask  and  repeat  until  all 
is  dissolved.  Then  dilute  to  1  litre. 

1  c.c.=  0*1  per  cent.  Mn  on  !•!  grm.  samples. 
=  -001734  grm.  Cr  as  Cr03. 
=  -005584  grm.  Fe. 

Permanganate  of  Potassium,  for  oxidizing  phosphorus  : 

Potassium  permanganate     .         .          30  grm. 
Water  up  to       ....       1000  c.c. 

Peroxide   of  Hydrogen,    for   titanium   and   vanadium 
estimations : 

Sodium  peroxide          .         .         .        6-7  grm. 
Sulphuric  acid  (1:3).         .         .        250  c.c. 
Water  to  ,  1000  c.c. 


APPENDIX   I  115 

Dissolve  the  peroxide  in  the  acid  and  dilute.  The 
solution  is  roughly  decinormal. 

Starch  Solution : 

Take  about  a  level  teaspoonful  of  starch,  and  make 
into  a  thin  paste  with  a  few  c.c.  of  water.  Add  two  or 
three  drops  of  saturated  zinc  chloride  solution  and  pour 
into  400  c.c.  of  boiling  water.  Boil  for  one  minute  and 
allow  to  settle.  The  cell  walls  will  quickly  subside  and 
the  clear  supernatant  liquid  may  be  poured  off  and 
used. 


Sulphate  of  Iron  and  Ammonia,  equivalent  to  standard 
bichromate : 

Pure  crystallized  ferrous  ammonium 

sulphate          ....  22-6  grm. 

Concentrated  sulphuric  acid         .  100  c.c. 

Water  up  to       .       ,.        .         .  1000  c.c. 

Add  the  sulphuric  acid  to  about  500  c.c.  of  water  and 
dissolve  in  it  the  ferrous  ammonium  sulphate.  Oool  and 
dilute  to  1  litre. 


Sulphate  of  Iron  and  Ammonia,  equivalent  to  deci- 
normal permanganate : 

Pure  re-crystallized  ferrous  ammonium 

sulphate          .         .         .         .39-1  grm. 
Concentrated  sulphuric  acid          .        100  c.c. 
Water  up  to       ....       1000  c.c. 
Prepare  as  for  preceding  solution. 


Il6  MODERN   STEEL   ANALYSIS 

Sulphuric  Acid,  for  phosphorus  determination : 

Concentrated  pure  sulphuric  acid  .       2-02  c.c. 
Water  up  to       ....       1000  c.c. 
1  c.c.=  '0001  grm.  P. 


Sulphuric  Acid,  decinormal : 

Concentrated  sulphuric  acid       "  .    „  2«72  c.c. 
Water  up  to       .         .         .  1000  c.c. 

This  acid  must  be  standardized  against  ^  sodium 
carbonate. 


Thiosulphate  of  Sodium,  for  volumetric  sulphur  estima- 
tion: 

Crystallized  sodium  thiosulphate  .       15-50  grm. 
Water  up  to       .         .         .      '  W      1000  c.c. 
1  c.c.=  1  c.c.  iodine  =  -001  grm.  S. 


Titanium  Standard : 

Pure  titanium  dioxide       £t^e     *>   0-8340  grm. 

Fuse  with  8-10  grm.  of  sodium  carbonate.  Dissolve 
in  a  mixture  of  50  c.c.  water  and  50  c.c.  strong  sulphuric 
acid,  evaporating  until  solution  is  complete.  Then 
dilute  to  500  c.c.  1  c.c.  =-001  grm.  Ti. 


APPENDIX   I  117 

Tartrate  of  Ammonia,  for  keeping  Al  and  Fe  in  solution  : 

Tartaric  acid      ....        340  grm. 
Ammonia  (-880)           ...        500  c.c. 
Water 500  c.c. 

Mix  the  ammonia  and  water,  add  to  the  tartaric 
acid,  and  filter  if  necessary.  30  c.c.  of  the  solution  will 
keep  1  grm.  Al  in  solution. 


Vanadium  Standard : 

Pure  vanadium  pentoxide    .         .   0-1778  grm. 
Sulphuric  acid,  cone.  ...          10  c.c. 
Water  to 1000  c.c. 

Dissolve  the  vanadium  pentoxide  in  the  strong  acid 
with  the  aid  of  heat  if  necessary,  and  dilute  to  1  litre 
when  cool. 

lc.c.=  -0001  grm.  V. 


n8 


APPENDIX  II 


ANALYSES  OF  DIFFERENT  STEELS 
AND  ALLOYS 

ALTHOUGH  steel  is  seldom  bought  and  sold  on  chemical 
analysis  alone,  specifications  frequently  impose  limits 
on  the  proportions  of  the  various  constituents,  especially 
of  carbon,  silicon,  manganese,  sulphur,  and  phosphorus, 
which  may  be  present. 

The  following  details  of  the  amounts  of  various 
elements  commonly  present  in  different  classes  of  steel 
will  serve  as  a  guide  to  what  may  be  expected  in  good 
quality  British  steels,  but  it  may  easily  happen  that  steel 
admirably  suited  to  its  purpose  may  be  of  a  composition 
not  falling  within  these  bounds.  The  ferro-alloys  are 
typical,  but  alloy  steels  of  the  most  varying  composition 
may  be  encountered. 

C              Si  Mn           8  P 
Axles 

Not  above  Under  Under 

0-3  ±0-05        0-2  0-6-1-0        -046  -045 

Fishplates 

Under  Under      Under 

0-15-0-25          0-06  0-06          0-08 


APPENDIX    II 


G 


Girders 


Si 


Mn 


S 


Acid  open 

hearth  0-15-0-25          0-06         0-80         0-06 
Basic  open 

Do. 


hearth        Do. 
Hammers 


Do.  Do. 


0-50-0-75         0-2  0-2 


0-02 


119 
P 

0-06 
0-04 

0-03 


Cold  Chisels,  Knives 

1-0-1-3  0-2  0-3       -015-02    -015-02 


Rails 


Acid 


Under 


Bessemer  0-35-0-50  0-06-0-10    0-7-0-95     0-08 
Basic  open 
hearth      0»45-0-65  0-65-0'90     0-06 


Razors 


Under 
1-3-1-5  0-2  0-2  0-020 


Springs 

Under  Under 

Laminated  0-45-0-70         0-25  0-5-0-8       0-04 

Under  Under       Under 

Spiral           0-8-1-3           0-12  0-8         0-035 


Tyres 


Under      Under       Under 
0-35-0*70         0-35          0-»         0-046 


Under 
0-08 
0-06 


Under 
0-020 


Under 
0-035 
Under 
0-035 


Under 
0-045 


120 


MODERN    STEEL    ANALYSIS 


STEEL-MAKING  ALLOYS 


Ferro-chrome 


Blast  Furnace                 Electric  Furnac* 

c 

9 

0-5-9-0 

Si 

under  1 

S 

•05 

all  very 

P 

•05 

low 

Mn 

•4 

Fe 

30-45 

19-27 

Or 

45-60 

60-70 

Ferro-manganese 

English 

Russian 

C 

5-7 

7 

Si 

0-1-0-7 

1-5 

S 

Trace 

Trace 

P 

0-1-0.25 

0-3 

Mn 

50-90 

91 

Ferro-molybdenum 

C               0-3-6-5 

Si            0-05-0-20 

Mn         under  0-2 

S             0-02-0-05 

P             0-01-0-03 

Mo              50-85 

Ferro-nickel 

C             0-5-1-0 

Si            0-1-0-3 

Mn         under  0-3 

S            under  0-04 

P             0-02-0-04 

Ni              25-75 

APPENDIX    II 


121 


Ferro-silicon 


Low  Grade 


Electric  Furnace 


c 

1-2 

C 

0-1-0-5 

Si 

8-20 

Si 

25-90 

Mn 

1-4 

Mn 

0-1-0-3 

S 

0-015-0-05 

S 

0-01-0-04 

P 

0-04-0-15 

P 

0-04-0-20 

Ferro-titanium 

Low  Grade 
C 
Si 
Mn 
S 
P 


Ti 

Ferro-tungsten 


0-5-0-8 

0-05-0-40 

under  0-1 

0-02-0-03 

0-03-0-05 

10-12 


High  Grade 

0-5-3-0 

0-7-1-3 

0-2-0-3 

0-02-0-05 

0-02-0-03 

50-60 


C 

Si 

Mn 

S 

P 

W 


0-4-3-3 
0-1-1-9 

•05 

0-01-0-10 
under  0-05 
50-85 


Al,  Ni,  and  Or  sometimes  up  to  1  per  cent. 


Ferro-vanadium 


C 

Si 

Mn 

S 

P 

V 


1-0-4-0 

0-1-0-4 

0-15-0-6 

0-03 

0-03 

35-55 


122  MODERN 

Molybdenum,  metallic 

C 

Si 

Mn 

3 

P 

Mo 

Al 


STEEL    ANALYSIS 

0-5-5 

under  0-5 

under  0-1 

under  0-05 

absent 

94 
sometimes  up  to  1  per  cent. 


Nickel,  metallic 

C  Trace-0-2 

Si  Trace-0-2 

Mn  and  P  Traces 

S  Trace-0-05 

Cu  0-1 

Fe  Trace-0-50 

Co  up  to  3 

Mg  and  Al  Traces 


Spiegeleisen 

English 


Silico  Spiegel 


Silico  Manganese 


I 

n 

C 

5 

1-2 

0-20-0-25 

0-20-0-25 

Si 

0-4-1-0 

10-15 

25-30 

21-26 

Mn 

10-25 

20-25 

65-70 

50-55 

S 

0-01 

0-01-03 

Trace 

Trace 

P 

0-05 

0-015 

-10-13 

•10-13 

Cu, 

Ni,As 

Nil 

Nil 

Tungsten,  metallic 

C 

Si 

Mn 

S 

P 

w 


APPENDIX  II 


0-1-0-3 

0-5 
under  0-2 

Nil 

Nil 
97-99 


123 


;,  Al,  and  0    up  to  1  per  cent, 


ALLOY  STEELS 

Mushet  Self-hardening  (Air-hardening)  Steel 


C 

2-15 

Si 

0-10  to  1-3 

Mn 

1-5  to  3-0 

S 

0-010-0-50 

P 

0-010-0-80 

Cr 

0-3-5 

W 

5-10 

High-Speed  Steels 
Typical  Analysis 


C 

0-7 

Si 

0-05 

Mn 

0-10 

S 

0-010 

P 

0-010 

V 

0-30 

W 

18-0 

Cr 

5-7 

124  MODERN   STEEL  ANALYSIS 

The  composition  of  these  steels  is  very  variable  and 
may  range  within  the  following  limits  : 

C  0-3-1-3 

Si  0-04-1-4 

Mn  0-05-0-30 

S  0-010-0-060 

P  0-010-0-040 

V  under  1-0* 

W  10-25 

Mo  0-8 

Or  1-5-6 

*  As  a  rule,  but  varies  within  wide  limits. 


INDEX 

AOBTYLDIOXIME,  see  dimethylglyoxime,  56. 
Aluminium,  effect  on  steel,  15 
estimation,  15 

influence  of  other  metals  on,  16 
Apparatus,  11 
Appendices,  107 
Arrangement  of  work,  8 
Arsenic,  estimation,  17 
Atomic  weights,  103 

BAKING,  7 

Barium  sulphate,  behaviour  of,  1 

Beaker  rack,  12 

Blair,  100 

Blanks,  8 

Boats  for  combustions,  25 

Brearley,  52,  53,  94 

Burette  stand,  14 

CABBON,  discussion  of  methods  of  estimation,  19 
estimation,  colorimetric,  21 
direct  combustion,  22 
separation  and  combustion,  26 
in  special  steels,  26 
Chromium,  29 

estimation,  gravimetric,  29 
volumetric,  30 
rapid  volumetric,  31 
effect  of  other  metals  on,  31 
qualitative  detection,  29 
Cobalt,  33 

cyanometric  estimation,  33 
gravimetric  estimation,  33 
125 


126  INDEX 

Cobalt,  estimation  in  presence  of  other  metals,  16 
Colour  carbon  estimation,  21 
Combustion  tubes,  23 

boats,  25 
Copper,  36 

estimation,  36 

effect  of  other  metals,  37 

solution  for  separating  carbon,  26 

DIBECT  combustion  of  carbon,  22 
Draining  board,  11 

EVAPORATION,  7 

FILTERING  stand,  1 3 
Filtration,  4 

asbestos,  6 

cotton  wool,  6 

by  pulp,  5 

GRAPHITE  in  pig  iron,  7 
Gregory,  31,  97 

HOT  plate,  7 
Hydrogen,  39 

estimation,  39 

IBBOTSON  and  Brearley,  52,  53 

MANGANESE,  42 

estimation,  gravimetric,  43 

volumetric  with  bismuthate,  44 

with  ammonium  persulphate,  45 

mechanicalized,  46 
influence  of  chromium,  46 

of  titanium,  49 

of  tungsten,  50 

of  vanadium,  48 
in  ferromanganese,  50 
in  spiegeleisen,  50 


INDEX  127 


Measure  rack,  11 
Molybdenum,  52 
estimation,  52 

in  presence  of  tungsten,  53 

NICKEL,  54 

detection,  54 

estimation,  volumetric,  55 

with  dimethylglyoxime,  56 
influence  of  other  metals,  57 
Nitrogen,  58 

blank  determination,  61 
estimation,  59 

OXYGEN,  62 

estimation,  63 

condition  of  sample  for,  66 
blank,  66 

PHOSPHORUS,  68 

estimation,  long  method,  70 

mechanicalizcd  method,  72 
quick  method,  68 

RACK  for  beakers,  12 

for  flasks,  13 

Results,  absolute  value  of,  8 
Ridsdale,  46,  72 

SAMPLING,  9 
Silicon,  74 

estimation,  74 

in  ferro-silicon,  75 
in  presence  of  other  elements,  77 
in  silicious  alloys,  76 
Stand  for  burettes,  14 

for  filtering,  13 
Sulphur,  79 

estimation  by  evolution,  79 
blank,  85 


128  INDEX 

Sulphur,  estimation,  gravimetric,  82 
in  special  steels,  85 

TITANIUM,  88 

estimation  by  colour,  88 
gravimetric,  89 
volumetric,  91 
in  ferro  titanium,  90 
Tungsten,  92 

estimation,  92 

in  presence  of  other  metals,  93 

URANIUM,  94 

VARIATION  in  composition,  9 
Vanadium,  96 
detection,  96 

estimation,  colorimetric,  99 
gravimetric,  100 
volumetric,  101 

WEIGHING,  2 

Wet  combustion  of  carbon,  26 


BALLANTYNE    AND     COMPANY, 
TAVISTOCK  STREET  COVENT  GARDEN 
LONDON 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $I.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


J«N    31  ;ig> 

KB     1    1935 

Alir    I  1336 

SEP  21  1939 

fcufto  °4  1941 

,. 

nrr  10  'fq4fi 

ULu  *-" 

LD  21-100m-8,'34 

UNIVERSITY  OF  CALIFORNIA  LIBRARY 


